A/N: Warnings for blood and needles (within the context of giving blood). Cancer mention, panic attack, past death mention (minor character), car accidents.

Giving blood is kind of my weird hobby; I've donated 24 times since 2012, which is like 12 liters total. I'm O-positive! :) As such, this fic is heavily based on my own experiences, although it should be noted that at no point did I ever have a gorgeous phlebotomist like Aang to hold my hand throughout.

Check out the second chapter, which contains notes that differentiate fact from fiction as well as some author TMI :)

One

The first time Zuko donates blood, he doesn't expect to lose quite so much of it.

He goes through a few tedious preliminaries. The phlebotomist who checked him in—Sokka is his name, a tall, muscular type with a sprightly wolftail sprouting off his trendy undercut—has him fill out a long medical history questionnaire on a laptop. Zuko fills in almost unanimous no's—things like 1) Have you been out of the country in the past three years? 2) Have you taken aspirin in the last seventy-two hours? 3) Do you have any relatives with Creutzfeldt-Jakob disease? What even is that? Even if any of his relatives had it, he might never know, considering his strained relationship with most of his family.

Upon the completion of the prerequisite rituals, Zuko follows him out to the floor and lies down as instructed on the pleather reclining chair, where he is fitted with a pressure cuff and dabbed with iodine at the crook of his right elbow.

"You'll feel a little poke, but it's never too bad," Sokka tells him cheerily. What follows is more a stabbing pain, like his vein is being torn apart, like a set of pincers digging tightly into the flesh of his arm. "You want anything to drink? You look kind of peaky."

He shakes his head no, not trusting himself to speak. It hurts, but it's not unbearable, and besides, it's for a good cause, no reason to complain.

A dull, muted ache sets in, numbing his arm, and he lies with his ankles slightly elevated. The floor is orderly and neat, six beds arranged in two rows with armrests on the left or the right depending on which arm is preferred. Two other beds are occupied, and another phlebotomist to Zuko's left bends over one of them, intently palpating veins.

"Oh, stop showing off, Aang, we all know you can stick any vein, even one with the most erratic course." Another staff member, who looks like she could be Sokka's sister, passes by on her way to the next bed, hands full with an empty blood bag and supplies.

"Not showing off, just trying to find the best draw site to give us the least pain and the quickest drain." His voice is a bountiful murmur, soft and reassuring. He notices Zuko watching him and flashes him a quick smile at his little pun.

Zuko hurries back to staring at the dim fluorescent lights above. The staff murmur to each other in the background, but slowly, silence drops, curtain-like, and a dusk-grey film stretches across his vision, a heavy blanket draped over his eyes. Out of curiosity, he leans over to look at the tubing attached to the needle, watching the blood leave his body.

"Almost done!" Sokka chirps, fiddling with a clip attached to the tubing. "Still feeling okay?"

He nods. His thoughts are viscous, like his blood flowing through the burgundy aqueduct. He's never donated before, but Ty Lee, a coworker, had reassured him that "It's the best thing ever! It makes your aura all glowy and pink! Plus didn't you say you're O-negative?"

That bit, at least, was true, and enough to convince him as a universal donor to give blood and save lives. It's not like he has anything else to do during his lunch break besides more work.

The bag is nearly full. A kink in the tube diverts the flow into six labeled tubes, test samples to make sure the blood is safe to be used. That done, Sokka prepares to remove the needle and reaches for something on a side table, absently brushing against Zuko's arm with more force than intended. The movement tugs on the tubing, and before he knows it, he dislodges the needle and violently knocks it to the ground.

The bubble bursts: the moment is shattered. Venous blood wells up suddenly, dark and bright against Zuko's skin, a trickle, then a stream, then a torrent.

"Oh my god," Sokka gasps. "Oh… shit… shit, I'm so… stupid—" He frantically scrabbles for gauze from the work station, knocking more bandages and supplies onto the floor in his panic. Zuko stares in shock as blood trickles down the slope of his arm. It's weird how it looks outside of his body, not as gooey as in movie effects, fountaining up like the center of a koi pond, or the oily, bubbling froth of overheated cheese pizza, getting thinner and more watery as it spreads out and smears against the armrest. His heart beats quicker, his left fist clenches abruptly, his breath catches, then comes faster and faster, and he can't seem to summon up the air to give voice to his fear that he is bleeding out for the love of all that is good—

"Easy there, I've got you." Another pair of hands drifts into his field of vision, long blue stripes angling their way up past bare elbows, and it's…Aang? His mind belatedly supplies, who has a sturdy patch of gauze, folded in quarters, pressed tightly to his puncture site, other hand resting on his shoulder. "Are you okay?"

"Yeah…" he manages, his voice blurry. "I… I'm fine."

There's a slight retching sound from the floor. "Sorry… I'm so sorry," Sokka mumbles, hand over his mouth. "I… I messed up—"

"No, Sokka, it's fine," Aang says firmly. "It was an accident, and it's not your fault. Katara, could you give me a hand?"

"Already on it." She brings over more gauze and alcohol cleaning pads, tearing a few squares open for him. "I'll clean up the floor. Sokka, come on. You should sit out the rest of this shift, you look worse than your patient."

"Don't like blood when it's not in the bag," he says faintly as she pulls him to his feet, indeed looking much greener than Zuko feels. "It smells like…" He trails off, and Katara nods as she guides him away to the refreshments table and sits him down with a bottle of water.

Aang has Zuko raise his arm up to lessen the flow of blood against gravity. "You're going to be tired of me asking this by the time we're through here, but are you really okay?"

I wasn't, but now that you're here, I am, is oddly the first thing that pops into his mind. Maybe blood loss is making him delusional? There's something so relaxing about the smooth glide of Aang's gloved fingers over his skin, making sure all the blood is wiped away; his gentle grip as he eases Zuko's arm back down to wind a red elastic bandage around the gauze pad.

"I'm fine." His throat is parched and his voice small and mousy, which does nothing to convince Aang he's not in shock. "Nothing that an afternoon off work won't fix."

Aang laughs. "A great excuse." He sorts out the sample tubes and the now-full blood bag. "Where do you work, by the way?"

"New York Philharmonic, assistant to the music librarian at the Lincoln Center." He's learned to append this bit every time someone asks, otherwise they assume he's some kind of virtuoso, which couldn't be farther from the truth.

"Oh, that's not far from here! Don't mind if I check up on you from time to time, yeah? I'd feel so guilty if you fainted or fell because of this." He winks mischievously, and even though Zuko knows he's joking, his heart leaps a little at the thought of seeing Aang again.

Two

Eight weeks later, he gets his chance.

Eight weeks, because that's the minimum time he has to wait between donations for his body to replenish ten percent of its blood volume. He makes an appointment for the earliest time slot he could manage and even volunteers to work later that day in exchange for the morning off so that he can carve out plenty of time to get to the Red Cross.

"I'm surprised you're going back after that disaster of a first time," Ty Lee reacts when he tells her about the arrangement. "But your aura has seemed a lot pinker since you went, so maybe it's doing you some good."

It has nothing to do with his aura, but he agrees, because he's not about to tell her that he's going back to see a certain someone. Then she'll pester him to no end about who it is.

"Hey, Zuko!" Sokka greets him by name. "So glad you're back! I didn't expect to see your name on today's list of appointments. Sorry about last time." He pushes the sign-in sheet towards Zuko without making eye contact, rubbing the back of his head in nervous avoidance.

"It's okay," Zuko says, and he means it. "I survived, and I'm back for more. I even did a RapidPass today." He found out that he can answer the questions about Creutzfeldt-Jakob and other ailments on his phone ahead of time so that they can skip that part of the process.

"Awesome! Well, I think Aang over there is free to get you started."

Indeed, Aang waves at him in brilliant recognition from one of the check-in booths. "You're back!" He looks so pleased, bright smile stretching from ear to ear as if this one repeat encounter is enough to make his whole week.

"You didn't come check on me, so I had to come back to prove I didn't… suffer any adverse effects from last time."

There's something about Aang that makes him throw all caution to the winds and act like a lovelorn fool. To Aang's credit, he doesn't look taken aback or even confused at this parody of flirting and carries on with the intake process. He extends two fingers to rest over Zuko's radial pulse, and once again, Zuko notes the long blue arrows and stripes tattooed up his arm and disappearing into his sleeve, mirrored over the top of his bare scalp—a bold statement even here in New York City, where you get all sorts.

"75, good. And your blood pressure…" With quick, deft movements, he wraps the cuff around Zuko's upper arm and presses the diaphragm of his stethoscope to Zuko's brachial pulse as he inflates. It gets uncomfortably tight up in the 150s, but Zuko focuses on how Aang concentrates hard on listening to his heart sounds through the stethoscope, watching the needle on the sphygmomanometer drift downwards (he only knows that term because Aang told him seconds earlier, counting the syllables off on his fingers with coy diligence).

"126 over 66, quite normal," Aang reports, deflating the cuff completely and releasing Zuko's arm. "That's always the hardest, estimating blood pressure. I nearly failed that part of my certification test."

"What made you want to become a phlebotomist?"

"Actually, I've always wanted to be on the opposite end of the needle, giving blood instead of drawing it, but I can't because I had leukemia when I was a kid. Say 'ah,'" he instructs, presenting a thermometer to Zuko.

He closes his mouth around the probe, now unable to speak, but Aang heads off the words in his eyes with a sheepish grin. "No need to look so sad; you won't be attending my funeral tomorrow. It was awful while I was in and out of the hospital for ages, but I've been in remission for sixteen years, and I don't plan to go back soon." The thermometer beeps, and he pulls it out. "98.2."

"Is that why you…" Zuko runs a hand over his own hair, referring to Aang's lack thereof. He doesn't mean to be rude, but the more he learns about Aang, the more he is drawn to him, a moth to a candle flame.

"Yep!" The last step is to test hemoglobin levels, and he patiently watches as Aang pricks the pad of his right middle finger to get enough blood onto the glass slide. "To show solidarity with cancer patients and normalize the experience. Hair is so overrated—no offense, your hair is lovely." He ruffles a playful hand over the top of Zuko's head, and Zuko nearly combusts on the spot.

"Thanks," he manages without his voice cracking.

Aang slots the slide into the hemoglobin analyzer and picks up the band-aids he'd opened in advance, just in time to defuse the blood that wells up anew. "I'll have to tell you the story about my tattoos another time; I know you're wondering. Everyone does."

"Why another time?"

"Well, I have to keep you coming back for more, don't I?" The analyzer beeps, and Aang frowns at the level. "Zuko, your hemoglobin's too low. Have you been eating properly?"

What? No, it can't be. Low hemoglobin means he can't donate today.

"I can try the other hand," Aang offers. "Sometimes warming up your hands can help circulation and increase your count." He takes Zuko's left hand and rubs the fingers vigorously between his palms, totally ignorant that Zuko can do it himself but much prefers it this way.

It's pathetically charming how for once in his life, someone is so attentive to his wellbeing, and he basks in the sensation of Aang's hands bathing his own in warmth. It's futile, though, because the second draw is still too low.

"Sorry, Zuko." He notes how his face falls in disappointment. "12.5 is really too low. But this only defers you for twenty-four hours, during which you have plenty of time to bulk up!" He pokes his head past the dividing wall of the booth. "Hey Sokka, what was that place you recommended? The classy steakhouse nearby?"

"Tuscany's? Oh, don't get me started—that place is ah-MA-zing! I had their veal chops once, and I didn't eat again for a WEEK, it was so good!" Sokka, having gotten started, doesn't seem likely to end anytime soon, waxing eloquent about its praises. "Perfectly grilled, just that level of medium rare that melts on your tongue, it's heaven in red meat. Definitely more of a date night place rather than a casual weeknight, it's uh, really expensive…" He peters out, mentally estimating Aang and Zuko's combined incomes versus monthly rent.

"Yes, thank you, Sokka, we get the point." Aang turns back to his crestfallen patient. "Zuko, treat yourself. You really need to boost your iron and hemoglobin, or you'll be collapsed on the street outside, and then what would I do without you?"

"Do you… would you like to… wh-when does your shift get off?"

Damn it, Zuko, heberates himself. Way to fail at asking someone out. Now watch it get all awkward as he tries to turn you down without hurting your delicate ego.

"Oh, I don't eat meat, but thanks for inviting me," Aang says sincerely, without a hint of disgust at Zuko's lame attempt. "Don't wait for me, though. Your priority now is getting a decent lunch. Go."

His tone is mock-imperious, but Zuko hurries to obey.

"Zuko?"

He pauses, hope swelling in his chest—maybe they can go to a vegetarian restaurant? Spinach has a lot of iron, right?

"I haven't forgotten, I still have loads to tell you the next time you're here. Don't make me wait too long, yeah?"

.

Sokka watches as Zuko flees the room, face flaming. "Boy, he's got it bad, Aang. I've never known you to be that much of a charmer."

"Don't say that, Sokka. Aang has a wonderful personality, and unlike you, Zuko doesn't seem the kind of guy who thinks that muscle tone is correlated with attractiveness," Katara says rather severely.

"You wound me," Sokka clutches his chest in dramatics. Aang quirks a smile at their banter, but in his head, he counts down the hours until Zuko can possibly visit again.

Three

"You didn't get to give blood? But your aura's pinker than ever!" Ty Lee squints at him suspiciously when he tells her about yesterday's debacle at the Red Cross. "It's something else, then. Come on, Zuko, spill."

"There's nothing to spill." He picks up another stack of music for this evening's masterclass and laboriously begins to sort it by instrumentation so that the performers can get their pieces in concert order.

"You met someone, didn't you?"

"How can you possibly know that?" He despairs of ever hiding anything from her. "And no, that doesn't mean that I did. Your conclusion is baseless and completely unfounded."

"Eh, you always get redundant in your speech when you're trying to lie." Ty Lee knows him too well. "Baseless and completely unfounded? He must be really gorgeous."

.

"Zuko, are you sick? Your temperature's 99.6."

"Maybe he's… lovesick," Sokka contributes unsolicited, even though he's not supposed to be entering an already occupied booth.

"Sokka, go away, you're violating patient privacy." To Zuko, Aang says, "Anything higher than 99.5 is technically running a fever, and you can't donate."

Oh, you've got to be kidding me. He hasn't been able to find time to come in for two weeks after the hemoglobin disappointment, and now he might be turned away again? "That's 0.1 degrees, though," he protests. "I don't even feel sick."

Aang puts the thermometer back in its nook and sighs, knowing what Zuko doesn't want to hear. "Yeah, you might be having an asymptomatic viral infection, but it could still be contagious, and we can't take that risk."

"Hey Aang, could you come help me with this donor? I can't for the life of me find any suitable veins." It's Katara, and Aang dithers for a moment before making up his mind.

"Sit tight, Zuko, I'll be back in no time and we'll repeat your temperature, see if it's low enough, okay?"

As soon as he's gone, Sokka pops his head back in, looking very devious considering that he's holding a cup of water out to Zuko. "Drink up!" he hisses, glancing over his shoulder to make sure Aang's not watching.

"What?" Zuko takes the cup, puzzled.

"Katara's not that bad at venipuncture. She made it up to distract Aang, now hurry up and drink!"

Still confused, Zuko empties the cup, which does seem to be just water and not poison. As soon as he's done, Sokka whisks it out of his hand and disappears. Moments later, Aang returns.

"All right, let's try again, shall we?"

Zuko dutifully takes the probe under his tongue, praying for a miracle, and the heavens deliver. "97.4."

"Oh good!" he says in relief.

"Zuko, is there something you want to tell me?"

Um. I'm stupidly in love with you? "No…?" he says, trying not to make it a question.

Aang smiles indulgently and shakes his head. "Never mind. It was only 0.1 degrees, after all. Let me just check." He reaches over and rests one hand on Zuko's forehead, a much more sensitive test for fever than a digitized thermometer, to be sure. Zuko holds his breath, counting the seconds through his pulse pounding in his temples (not accurate, way too fast), dizzy from his touch.

"All fine. Let's go."

He owes his eternal thanks to Sokka and Katara. He's not sure he could take being deferred for the second time in two weeks, especially with the chance for Aang to draw his blood.

"You said you were going to tell me about your tattoos," he reminds Aang as he's sitting in the chair watching him prepare the blood bag and tubing.

"Oh yeah, I did." He sets the supplies aside and wraps a pressure cuff tightly around Zuko's upper arm. "Make a fist for me."

Zuko clenches his fist, and Aang ghosts his fingers along the crook of his elbow to find a decent site for the blood draw. There's a slight discoloration at one point along the vein, the healed puncture from last time.

"I dropped out of medical school in my second year, three years ago now. Couldn't keep up with the work," he says with studied nonchalance. He doesn't sound like he wants to elaborate. "Plus I was going through some personal stuff of my own, so it wasn't a hard decision to make, in the end."

Zuko swallows his nerves, wondering if this is going to be more depressing than he'd originally expected—not that that makes him less interested in Aang and his story. If anything, he wants to know even more what brought him to where he is now.

Aang draws a couple of marks with a purple marker along the course of Zuko's vein. "Relax your fist, but don't move your arm at all."

He moves on to the familiar iodine swabbing for the requisite thirty seconds, looking at his watch as he daubs Zuko's skin with the brown liquid. "More than anything, it was a way to celebrate a new period in my life. In med school, you're not allowed to have tattoos in visible places, piercings besides the ears, or any sort of unusual body modification, all in the name of professionalism. I guess it harms the more conservative patients' sensibilities. So I went all out."

It's time for the needle, and Zuko readies himself for the pain. However, unlike the first time, he barely feels it after the initial, sharp twinge. Aang eases the needle in and covers the site with a square of gauze. "Gentle squeezes every ten seconds or so, keep the blood moving."

Zuko rolls the stress ball in his hand and squeezes as indicated, listening to Aang continue to explain his choices.

"The arrows I decided on as a symbolic element of guidance. Life's always moving in a specific direction, but you get bogged down in medical school and forget what that direction is: forward. I put them on the backs of my hands to remind myself every day, and on my forehead to remind others. Are you feeling okay?"

"Peachy." He can't imagine a better place to be, just hearing Aang talk.

"I must have been in some kind of elemental Zen mood when I made up my mind about the color. Sky-blue for water and for air, the elements of change and freedom."

There's a slight embarrassment to his tone, as if he thinks Zuko will dismiss him as overly sentimental—he doesn't. It makes sense in a gently transcendental way. Aang would probably get along great with Ty Lee.

Definitely not a good idea to introduce them. Knowing Ty Lee, she'll piece things together immediately and I'll never hear the end of it.

"I went to the tattoo parlor not long after I started training in phlebotomy. It was just going to be arrows on my forehead and hands, but then I thought, I'm a whole person. Every part of me should subscribe to the same philosophy, from my head to my heart to my toes."

That's dedication. Ever so slowly, Zuko's thoughts follow in the wake of Aang's words, and he processes his meaning. "Wait, you mean it's all connected? All the way down to…?"

Aang nods. "Down my neck, joined by branches from each arm, down the back, and splits at the small of the back—my pain tolerance is decent, but I don't have enough padding down there to justify getting stabbed over and over in the buttocks. So it crosses over the hip on each side and comes around to the front, down each leg to my toes."

How is he keeping a completely straight face? Zuko is dying inside. He closes his eyes, childishly thinking that Aang won't look at him and notice the blush setting in over his face.

It doesn't work. "Are you sure you're okay? Don't fall asleep on me now."

"Yes," he grits out. He opens his eyes again, avoiding Aang's gaze. "Totally fine."

Reassured, Aang briefly drops out of sight to attend to a shrill beeping: the blood bag needs to be shaken periodically to prevent coagulation. "If you really want to fit my life into a cookie-cutter metaphor," he says, popping back up, "you might even say that I got my tattoos after starting phlebotomy training to reflect the flow of blood through the body. That makes me, like, the ideal poster boy for the organization. Great, isn't it?"

Zuko considers it, minutely squeezing the stress ball in his hand. "Your life doesn't have to be a metaphor or represent some grandiose ideal in order to matter. It contains value in itself, just by virtue of being your life."

It's true, even if it sounds like a line out of a self-help manual. He's seen so many young artists in his line of work throwing themselves into their careers, dreaming of becoming Lang Lang 2.0 or the Next Great American Composer, only to be crushed by the unremitting plow of their Sisyphean boulder. That's not the point of music, of any art or career: to achieve something greater than the self or die trying. Sure, Azula succeeded, but at the cost of their relationship and more, things she didn't need to sacrifice but chose to anyways.

He does stun Aang a little bit now, judging by the quick widening of his eyes and his surprised smile. "Thank you, Zuko," he says. "That's the nicest thing I've heard in a while. I appreciate it."

The words, in any other mouth, would sound stiff and formal, but Zuko drinks in his sincerity and wholeheartedness.

"Almost done," Aang reports. "You're a quick one."

He wouldn't mind bleeding slower if it gave him more time with Aang. No, he wouldn't mind a bit.

Four

Several months pass this way. Zuko comes in every eight weeks, making sure to have a hamburger or pork chops or something filling the night before, drinking extra water (both in general and right before taking his temperature), and taking all manner of precautions to ensure he can donate regularly. As a bonus, the staff at the center always make sure to steer him towards Aang when he arrives, and he doesn't mind waiting a few minutes if he's busy with a patient.

He tells Aang about his work, about Ty Lee, about what sessions are going on at the hall tonight, about how some flutist pitched a fit at Zuko because she couldn't find her sheet music and thought he'd misplaced it (it was right there on the stage with her, but she'd accidentally left it on the stand two seats in front of her when they'd shifted seating arrangements between pieces, and her face was priceless when Zuko pointed it out).

Aang always listens patiently, sometimes asking questions about the logistics of running the music library and the daily programming. In turn, he volunteers stories about particularly difficult patients and the most incredible misconceptions they have about blood typing.

"Once, a donor told me that both of his parents were B-negative. He'd seen their medical paperwork when they were hospitalized for something or other. And he said, 'So it makes sense that I'm B-positive, because their two negatives cancel out.'"

"That's… not possible, is it?" Zuko asks. Even with his elementary understanding of blood types, he knows that they don't follow the multiplicative rule of negatives.

"Definitely not possible."

Aang bends down to adjust the blood bag a fraction. His head is level with Zuko's hand where it dangles off the armrest, and if he were to extend his fingers a bit, they could smooth over his bare skin, blue on pale.

"He was devastated to learn that his mother must have had an affair with someone who was Rh-positive. There's no other explanation." Aang straightens up and quirks a bemused smile at the intent gaze landing on him. Zuko snatches his eyes back, curling his fingers around his stress ball and pretending nothing is amiss.

"Mystery solved," he says lightly.

"I know, right? I should be on CSI or something, helping them catch the murderer by blood typing," Aang jokes. "Detective Aang has a nice ring to it."

.

Zuko doesn't think he ever smiles so much as when he's around Aang. It's as easy as breathing. Day in and day out, he likes his work well enough: it's a stable job, and he can be around music all day without the pressure of having to perfect a performance. That's Azula's purview, not to mention why their father practically disowned him in favor of her. There's not much incentive to shine here. People like him don't get a standing ovation for making sure that the sheet music is always filed in perfect order with optimal page turns, that the violinists all have consistent bowings marked in their parts because they can't be assed to remember themselves, that the stage is always set up just right to maximize each musician's limited personal space, and all the minutiae that go into producing the magical performances that opulent crowds flock to every evening.

Aang gives him space from that monotonous track, clearing his mind of all troubles with a smile that could replace the sun, his laughter a breath of fresh air and his touch like soothing water, cool and comforting. He's beautiful, and Zuko has no idea what to do about that.

.

One day, though, his joyful pattern is broken, because Aang is not there.

"Sorry, Zuko." Katara shakes her head as soon as he walks in the door after getting off work early; it's only three o'clock. "Aang has the afternoon off, to visit a friend, he said. Suki can take you: he traded her for the morning shift."

Since he's already there, he lets them take his blood. Suki is a sweet girl, and though she's new to the team, her expertise does not lag a step behind her colleagues. She gets him going immediately without any hitches, but all the same, he itches to leave. He could have made up an excuse and come back tomorrow. Then he wouldn't have to wait another eight weeks to see Aang after today. But who comes to a blood drive to see a person and not to give blood? They'd think he's hopeless.

Maybe it's the chill of January in New York, or maybe he didn't drink enough water afterwards, but the half-mile walk to the subway station seems longer and more tiring than before. He gets on the 1 line and rides three stops to 72nd and Broadway, switching to the 2 that takes him across the river to 149th and Grand Concourse. It's a long commute from work in the Upper West Side to home in the unpopular Bronx, but rent is rent, and it has to be paid. No way can he afford a one-bedroom in lower Manhattan on his salary.

From Grand Concourse, he'll catch the 4 towards Woodlawn. Well, whether or not I catch it depends on how fast I run. He hears a train pull up on the level above him. That must be it right now, shit, gotta run—

He sprints up the stairs to the green line trains, and sure enough, the 4 greets him, doors sliding shut moments after he slips in. Phew, I made it. Another train would have come in seven to eight minutes, but he's particularly antsy today and just wants to get home. It's five o'clock, and the train is packed, not quite chest-to-back all-up-in-your-personal-space level yet, but there aren't any open seats. He sidles up to one of the pole spaces near the door, heart still pounding from the uphill jog, and settles in for a long ride.

Before long, though, he knows something is amiss. His muscles feel weak, his head spins, and he sags against the pole, bumping shoulders with a stranger who is probably less than pleased at this breach of privacy.

What's happening…? He can't support himself. His knees are barely holding him up, and he grips the pole tightly, determined not to fall and make a fool of himself. Well, he already has done that, considering how he's reeling drunkenly in full sight of the whole carriage. It's likely not the worst case they've seen in the history of public transportation.

The long minutes pass, and the operator announces that they will be skipping a number of stops to avoid delays. That doesn't bode well for Zuko, and even as the announcement ends, he senses an overwhelming vertigo overcoming him. Somehow, his hearing seems dulled, as if he's listening from underwater. A cold sweat breaks out along his neck, and as he struggles to remain upright, he becomes distinctly, helplessly aware that his vision is fading to black.

It's terrifying to witness, as if his body is not his own, and he watches as the face of the passenger across the aisle winks out of sight, the darkness eating up every feature like a black hole. He can't see anything. His eyes are open, but it's completely dark. He could be staring someone unnervingly in the eyes and he wouldn't be able to tell a thing about them.

I have to get out. I can't die on the train here, in front of everyone.

He has to get out, but they're not opening the doors until the next stop, who knows when, and even if the train stopped, how will he get out if he can't see anything. He knows where he is because he's still somehow holding onto the pole and hasn't collapsed onto the floor, but it's a close thing, and his heart is thumping in his chest, his labored breaths a death rattle, a shaken sob hiccupping in his throat (don't let it out), he can hear the shift of passengers around him and the rub of soft fabric on sleek waterproof rain jackets and the muted murmur of tired professionals heading home and they all think he's drunk or crazy or having a mental breakdown but either way nothing that's directly affecting their lives right now so who cares—

"Zuko?"

Who…?

"Zuko!"

He turns his blind face from side to side, trying to localize the direction of that blessed voice.

"Zuko, I'm right here." It comes from right in front of him; he must have pushed his way through the entire carriage. "What's wrong? You're white as a ghost."

He can feel Aang's body heat radiating towards him when they're this close, his warm breath and warmer voice suffusing him with strength, and he summons up enough reserves to choke out the words. "Aang. Aang, I-I can't see. I can't see anything—"

"Relax. Breathe, Zuko, you're okay."

He's still clutching onto the pole like it's his own sorry life, but Aang seizes his hands, prying his frozen fingers off the cold metal, tugging him into an encompassing hug. How this is even possible, what coincidences brought them to the same place at the same time today, Zuko doesn't know, but he's grateful all the same.

"Aang… I'm scared. I'm so—I'm so scared…"

Strong arms shift to wrap around his back, pulling him to rest completely against Aang, and he lets himself go limp, the fight to remain standing no longer necessary. "You're okay Zuko. I'm here, I've got you."

He's still shaking, but Aang doesn't let him fall, rubbing calming circles between his shoulder blades, murmuring quiet nonsense in his ears without a care for what people are thinking. The solid, strong wall of his chest is so comforting, and some less-than-lucid part of Zuko's mind wishes they could stay this way forever, safe and untouchable. Aang smells of iodine prep swabs and…

"Flowers?"

"I was going to visit a friend," Aang explains, and even in his muddled state, Zuko feels a weak stab of jealousy, immediately fading to guilt. Of course Aang can visit his friends and give them flowers as he pleases. That's not for Zuko to impose on.

The air slowly starts to grow lighter, even though the suffocating number of people in the carriage hasn't changed. The empty black space in front of his eyes gradually resolves itself into the yellow and orange hues of Aang's hoodie, and it strikes him that he's never actually seen Aang wearing anything besides the scarlet Red Cross polo shirt.

Wait. He flicks his eyes up towards Aang's face. "I can see you!" he realizes, elated.

Oh thank God, he's not blind, he's not dying, he's not dead, and the first thing he lays eyes on are grey eyes wide and looking back at him, puzzled, then delighted, then serious again.

"Cover your left eye. How many fingers am I holding up?"

"Two?"

"Cover your right eye. How many fingers?"

"Four? Aang, is this really necessary?"

Aang nods, not a trace of mirth on his face. "People don't go temporarily blind for no reason. I have to check; humor me." He extends one arm out behind Zuko's head. "I'm going to move my fingers in your peripheral vision. Look straight into my eyes and tell me when you notice my fingers enter your visual field."

Zuko obliges since it seems so important to Aang, and he supposes it's not a bad idea to check if there are any lingering deficits.

"Follow the tip of my finger with your eyes only." He traces his finger to one side, then up, down, across to the other side, up and down again, ascribing the shape of an H and then zooming in towards his nose, forcing Zuko to go cross-eyed.

Satisfied with that, Aang takes out his phone. "Look straight ahead." He turns on the flashlight in his phone and shines the light in one eye. "Looking at your pupils—both should dilate in response to light being shone in one eye." He swings the light over to the other eye, repeating the test.

Overhead, the operator announces Burnside Avenue, and the train finally stops to let passengers off. Aang all but drags him out the doors and plops him down on an empty bench. The air is frigid with new rain but so refreshing after the cloying humidity of recycled breath.

Aang rummages around in his backpack (Zuko hadn't even noticed he was carrying one) and withdraws a bottle of water, snapping the seal and handing it to Zuko. "Drink."

Zuko accepts it and takes a long sip, realizing how dehydrated he's been. He leans his neck back against the bench, still woozy, and turns his head to see Aang frowning at him in blatant concern.

"What happened?"

His over-the-top worry tickles Zuko and curls the corners of his mouth up. "All done with your tests?"

"Don't give me that. If I were really being thorough, I'd still need to do a fundoscopic exam and a full neuro exam: sensory and motor testing, gait, coordination, reflexes, the whole gamut. Cranial nerves, too, for completeness' sake, though you don't look like you have any signs of palsy."

"I'm surprised you still remember everything from med school."

"Just the important things," Aang says, a sour look flitting across his features at the mention of that time. "Enough to diagnose your sorry head into oblivion, anyways." He pokes a stern finger between Zuko's eyes. "You're still not telling me what happened, but I can guess. You ran to catch your train after donating blood, and the oxygen deficit caught up to you after it started moving. You panicked, your system went into overdrive, using up even more energy, and your starved eyes gave out on you."

"Pretty much," Zuko admits. "Hey, what are you doing?"

Aang is obviously going through Zuko's coat pockets, but why? "Looking for your phone. Do you not keep it here like normal people do?"

"The inside pocket," Zuko tells him, too tired to get it for him. "Why do you need my phone? You have yours."

Aang locates his phone, warm fingers brushing against his chest and igniting the most stomach-turning tingling sensation on his skin—maybe he needs that neuro exam after all. "To give you my number, smart one. I'm not going to be able to sleep worrying about you unless you text me that you're fine—no, call me, I'm turning my ringer volume up to the loudest."

He hands Zuko's phone back. He's saved his contact as Doctor Aang.

"Bold of you to call yourself doctor."

"Doctorate degree in making sure you take damn care of yourself and stop risking your life to catch a train."

They make it back onto the next train, this car thankfully much less packed than the last. Zuko tries to sit up straight with a respectable distance between the two of them, but Aang jams himself right up next to him, a strong support. It's totally PDA and totally welcomed. The iodine scent has faded a little from the crisp air outside, but the fragrance of flowers remains.

They get off at Zuko's stop, and Aang insists on walking him the five blocks to his apartment.

"You said you were going to visit a friend." He tries hard not to sound accusatory.

Aang hears what he's not saying. "I was going to visit Gyatso, my mentor and the doctor who treated my leukemia when I was a kid." From inside his hoodie, he pulls out several stems of smooth, white, long-petaled flowers, tied together with a string. Their blooms are a little lopsided from being crushed between him and Zuko.

"It's his birthday, so I usually bring him his favorite Yulan magnolia. Jade lily—it's native to China," he explains. "Gyatso's in Woodlawn Cemetery now, but it doesn't grow there."

Oh. Now Zuko feels even worse. "I'm sorry," he mutters, looking at his feet. "I shouldn't have kept you."

"He wouldn't mind." Aang pulls one flower free of the bundle and tucks it behind Zuko's ear. Zuko wonders if he has died and gone to heaven. "Gyatso always said that helping those who need it the most takes priority over everything else."

Words to live by. "I'm very grateful to you, Aang, for everything," he says, plain and without embellishment; there are no truer words to be said. For everything I can't put into words, everything that you do for me.

"Oh yeah?" Aang's smile is a little devious. "What will you give me, then, to show your thanks?"

Zuko stops in his tracks, wondering what Aang is getting at. A kiss? More than a kiss? My life? All of these and more are on the table.

"Relax, you look like I asked for your firstborn child." Aang laughs. "How about you give me your word that you won't run after any more trains when you've just donated ten percent of your blood volume?"

"Fair enough."

He hugs Aang goodbye, not daring to ask him any farther than the doorstep, wondering, agonizing over whether something has changed about their relationship, or if this is how he is with everyone: tender, compassionate, selfless, the paradigm of his mentor's teachings.

He longs for more, but… he takes the flower from his ear and smells it, the citrus-lemon scent all that's left of Aang's receding figure. He will accept as much as he receives and give back in kind. Surely that's the best way to Aang's heart?

Five

"Hello, Zuko here," he answers the unknown number. Ty Lee throws him a dirty look as he leaves her to finish recategorizing the library's entire collection of Mahler's symphony scores by herself.

He freezes as he registers the words "emergency room" and "motor vehicle accident" in the same sentence as "Aang."

.

"Who's your emergency contact?" Aang asks after Zuko calls him later that night to verify that he didn't in fact keel over dead the moment Aang left him alone.

Zuko pauses, having to actually think about it. "I'm pretty sure I put Azula's name down on the HR forms when I first started working at the Lincoln Center because it was a required field. I might have put a fake phone number, though, 'cause I doubt she'd care if they called her saying I was in an accident. Uncle Iroh and my cousin Lu Ten would, but they live on the west coast, so that's not much help. What about you?"

"I think I put Katara down, since my parents are out-of-state too. Most people that I know in the city I met through work."

That makes sense. "But wouldn't it be useless if there was some incident at the Red Cross and you both were incapacitated? Who would they call for you, in that case?" He hates to imagine Aang possibly getting hurt.

"Then let's both change our emergency contact to each other," Aang suggests. "I don't want no one to know if something happened to you, Zuko. I wouldn't want you to be all alone in the hospital."

Zuko's heart may be melting, if that's even possible for an organ already filled with liquid. "Okay," he agrees, liquid heart and all.

.

The emergency room is four blocks from here. It's been a month since his unfortunate incident on the train, and he feels at the peak of his health. He stuffs his phone in his pocket and runs.

They don't actually let him see Aang for several hours while they're doing whatever scans or procedures are necessary on him, by which time he'd contacted Katara and Sokka as well. All three of them are on edge, Sokka practically tearing his hair out in agony, Katara pacing as if every step will bring them closer to the moment they get news about Aang's condition.

He'd been hit while crossing the street by a car turning right at a green light without looking. The only information they'd been able to get out of the nurse before she left again was that he'd suffered at least two fractured ribs, possible internal bleeding, and a concussion from rebounding off the windshield onto the ground. He's likely going to need a blood transfusion.

"I should have known when he didn't show up for work this morning," Katara laments. "I thought maybe he overslept, but that's just not like him."

Zuko says nothing, hunched over his knees, on the verge of throwing up. Aang could be dying, and there's nothing he can do but wait. It's the absolute worst place to be.

At length, they are ushered into a separate trauma bay where a harried-looking intern promises them that Aang's in anesthesia recovery right now and will be wheeled out to them soon. Not soon enough.

.

"Katara, Sokka, I thought you'd both be here."

Zuko turns to see a short woman with dark hair cut close around her face standing in the doorway. She's looking at them, but her pupils are cloudy white—she's blind.

"Toph! What's up?" Sokka asks. "I wondered if you'd stop by." To Zuko, he says, "Toph is our assistant manager for collections. She's a miracle. This hospital used to waste so much in blood products through improper handling until she stepped in and made them standardize protocols."

"She knows the fate of every blood bag that goes through this system," Katara seconds him. "It's really thanks to her that Aang's even got a transfusion."

Toph cocks her chin as Sokka is speaking. "Who else is here?" she asks.

"Uh…" Zuko stalls for a moment and decides against trying to shake her hand. "Hi, I'm Zuko. I'm a friend of Aang." He waves awkwardly, though she can't see it.

"Zuko?" The name seems familiar to her. "I'm sorry to correct you, Katara," though she sounds nothing close to it, "but you really have Zuko here to thank for that, not me."

"Huh?" Everyone says simultaneously.

She huffs out a perturbed sigh. "You've been telling me for months about a glorious O-negative benefactor who gives blood every eight weeks on the dot. No one does that, especially in a city this busy. People donate once and pat themselves on the back for the rest of their lives. Of course I was going to do my research on him. Zuko: haven't they spoken with you about power red donations? You can donate 2 units of blood every 112 days instead of 1 unit every 56 days. That way we can get your blood faster and you don't have to come back as often."

"Oh. Well, I…" He struggles to come up with an answer. Sokka comes to his rescue.

"Aang never brought it up with you because you're barely over the weight requirement. 130 for males, and your BMI as calculated is almost underweight. Your hemoglobin's never high either. He didn't want you to feel overtaxed."

He's grateful for the intervention, because it spares him having to explain to Toph that the real reason is that he would have to wait a torturous 112 days between visits, which is far too long to go without seeing Aang.

"How sweet. You lot of blood-sucking buffoons." Toph shakes her head ruefully. "He should have brought it up because as it turns out, Aang's O-negative too."

Katara gasps. "Toph! Watch your mouth with the HIPAA violations."

"Pfft, it's not his social security number or anything." Toph laughs. "Anyways, I just stopped by to let you know that Aang received Zuko's most recent unit of blood and to tell you to thank him for me, but now that that's done… toodles."

She's gone, and Zuko realizes that Sokka and Katara are staring at him with something close to awe in their eyes, just because he provided a unit of blood in Aang's time of need. It's kind of amusing, considering this is not the limit of what he would do for Aang if it were needed of him. Platelets, Aang? Hook me up to the apheresis machine. Need a kidney transplant? Here's mine. Want my heart to go with it? Take it too; it's yours.

.

Aang's pretty out of it, thanks to the sedation. Katara and Sokka hightail it back to work once they've confirmed he's breathing and talking and living, Sokka leaving Zuko with a very significant wink. He is tireless.

"Do I… know you?"

It's the anesthesia talking. "Of course you know me. I'm Zuko, remember?"

Aang considers this with pinched eyebrows and a languid finger probing at his nonexistent beard. "Are you my boyfriend?"

Zuko almost chokes on his next inhale. "I… no, I'm not."

Aang giggles. "Not right now, but let me tell you, you are so handsome and cute and gorgeous. You have to become my boyfriend, please?" He looks so hopeful, puppy-eyed and pleased with his prospects.

"Er…" How do I get out of this without hurting either anesthesia-Aang or real-Aang's feelings?

"Do I already have a boyfriend?" It suddenly occurs to Aang. "Because that would be bad if I did. Do I?"

Zuko sighs. He probably won't remember any of this when he actually comes to. "No, you don't."

"So you'll be mine, then?"

"…yes. Yes, I will."

"Yay!" He reaches for Zuko's hand resting on the bedsheet but misses it entirely in his somewhat uncoordinated state. Zuko takes pity on him and takes the errant hand in his own, and Aang draws it up to rest against his cheek, perfectly content. "I'm so happy, Zuko."

Oh, Aang.

Six

True to Zuko's prediction, Aang doesn't remember anything that transpired in his post-operative period. He's pretty sure that Aang would have said something about it or even apologized for making him uncomfortable, but their friendship continues without any such snags, and Zuko supposes that's the best possible outcome.

Aang does call him up not long after he's discharged home to thank him profusely and at incredible length for the blood. Zuko doesn't have the heart to tell him to stop, because he too is suffused with relief beyond words that he made the choice to donate that day, even though he didn't know his blood would end up with Aang. It's true that they could have requested units from external blood centers, but that would have delayed his transfusion and had significant consequences for his recovery.

Speaking of which, Aang recovers at a magnificent rate from his fractured ribs and bruised spleen. He does need a bit of help around the house for a few days, but he tells Zuko in no uncertain terms not to bother with the trip down to his place in Lower Manhattan ("Seriously, Zuko, I'll manage. It would tack on another hour to your daily commute, and besides, Katara said she'll stop by with groceries on the way home"). So he listens and tries not to feel too miffed about being kept on a long leash. Aang's got plenty to deal with already— there's no need to be overbearing at this time.

Aang still texts and calls almost every day, and at first, Zuko worries they'll run out of things to say outside the circumstances of giving blood that usually unite them. But his fears are groundless: Aang remains as spritely and cheerful as usual despite his injuries, and Zuko can't help but respond in kind. Even their silences stretch into periods of comfortable breaths and ambient noise, their only purpose to reassure each other that the other is still there, still glad to be on the line, the only thing connecting them.

"Have you ever thought about going back to med school?"

Aang hums quietly in consideration. Zuko's question is just that: a question, not a judgment or a devaluation of Aang's choice to drop out. "Not really. It's true that I was struggling academically, but I could have at least passed my exams if I'd pushed myself harder. It's more that I got disillusioned with the process."

He pauses, and Zuko waits for him to sort out his thoughts. He imagines Aang stroking his chin thoughtfully like he did that day in the ER. It might be a little stubbly—he doesn't know if Aang shaves every day or only for work, and if facial hair is included in his habit of shaving his head. He wants to know these things.

"Gyatso died halfway through my second year—motor vehicle accident like me. He was a professor at my school, and I would have looked up to him so much even if he hadn't been the one to cure me. He wanted to save lives in his work, and he did. I'm pretty sure everyone there does. But you just have to go through so much shit. Years of training even beyond your four years of school. Attendings and chief residents who grind you into the mud on your rotations because they're burned out and jaded by the system and need to take it out on someone who can't push back. Patients who don't follow the prescribed course of treatment, not because they don't listen to you or don't care about getting better, but because they don't have insurance to pay for their meds, or don't have the money to shop for healthier foods or quit their job full of environmental exposures or buy a car to drive to their weekly appointments…"

The pain in Aang's voice is so palpable. Zuko's heart aches upon hearing him and understanding how much he must have chafed in a system that purports itself to exist for the good of everyone under its auspices, but often perpetuates the same harms it claims to heal.

"I would have saved some lives in the end, as a physician in whatever field. It would never be enough, though. There would always be some patients beyond help, like Gyatso. With my current work, I know that the blood I'm taking is always going to try to save someone. Maybe they'll die, maybe they'll live. Either way, I'll know that I've done everything I can to help. Even if everyone thanks the attending physician for saving them and not the rest of the team, it's enough for me."

The silence after his pause this time is heavy with meaning, and he laughs awkwardly, trying to diffuse it. "Sorry, that was… that was a lot. I guess having a brush with my mortality influenced my answer to your question. Sorry, I don't mean to be macabre."

"No," Zuko finds his voice. "No, I know what you mean. About doing everything you can, even if from the outside, no one sees how much you do. I feel that way about my work too: how people only care about the performance and never realize what went on behind the scenes to make it happen. But I can't complain. We're the only ones who need to see our own efforts, so that we know we're making a difference in this shitty world."

"Beautifully put," Aang says, and it's only half joking. "You can't wait around for things like med school and car accidents to happen to you. You have to take action to shape your life and the world for the better."

It sounds like an invitation.

.

Sokka dutifully informs Zuko that Aang's back at work two weeks after the accident, even though Aang texts him the news not long afterwards. Zuko decides to stop waiting.

.

"Zuko, did you run here from the station?"

He frowns at Aang, wondering what could possibly be wrong this time. Aang still has two fingers on his pulse, a twitch lining his lips as if he's trying not to laugh.

"No, I didn't. I walked very slowly."

"Then why is your heart racing? 104 is way too fast."

He takes a deep breath. Aang can keep pretending not to understand why, but Zuko will have this out, heaven help him.

"It's beating so fast because it's longing to reach its other half with you."

Aang looks thunderstruck, and Zuko lets a small flush of pride come to the surface. The doctor has been outdone by his patient. He clearly wasn't expecting Zuko to have such a devastating comeback.

"You… you are…" Aang tries to find his speech, fails, gives up. "Oh. My. God. Come here—"

Aang kisses as he lives, without regrets, without falsehood, without fear, and Zuko pushes himself to embody the same. A fist in his collar pulls him up out of his seat, and he dares to sling his arms around Aang's neck, hands traversing his back, clinging to his waist, laying joyous claim to these parts that he has only touched before in a moment of weakness. Lips part, a prying tongue clamors to meet his own, and he welcomes Aang into his mouth, into his life, into their forever and beyond. He is so glad that they have stopped waiting and started loving, today and hereafter.

Sokka is another one who cannot wait any longer, and he barges past the wall of the booth to see what's taking Aang so long with Zuko, don't they know there are more donors waiting in line—

"Oh okay WELL THEN. If I'd known it was going to be oogies I'd have knocked first."

They break apart hurriedly, and Zuko tries to straighten out his collar and his hair to make it look less oogieish, if only to preserve Sokka's innocence.

"Can you please not use that word?" Katara grumbles as she comes to investigate the source of Sokka's outburst.

"Well, what word would be more suited to the occasion?"

"I don't know, maybe congratulations?" she suggests, smiling at the besotted new couple.

"Thank you," Aang says, his face even more radiant than usual, if that's possible.

"Thanks," Zuko echoes, a little dazed.

"Zuko, that was the most romantic line ever. You've outdone me. I'm never going to be able to live this down," Aang says, clutching Zuko's hands, blissfully unaware of the fact that they're now garnering attention from everyone on the floor as well. Sokka and Katara go to quell their curiosity.

"I outdid you when I gave you five hundred milliliters of my blood."

"You're going to be holding that over my head for the rest of my life, aren't you?"

He draws Aang close, tenderly running a thumb along his cheekbones, watching those grey eyes flutter closed. "Only if you let me."

Aang lets him, and with another kiss, they begin the rest of their lives.

A/N: A handy link (www dot redcrossblood dot org /donate-blood/how-to-donate/types-of-blood-donations/blood-types dot html) on the basics of blood typing, although there are a lot more factors that go into crossmatching than what's shown here. The only point of significance that I would add is that Aang, having O-negative blood type, can only accept O-negative blood, because he has antibodies against the A and B groups and Rh-positive groups. It's also a pretty rare blood type, so fortunately Zuko is around to give him his blood.

See next chapter if you want to read more of my ramblings :)