Author's Note: Thanks so much for the reviews! I'll definitely be individually responding, but wanted to get this out first. I hope you enjoy!

What Makes a Family

Part Two

"Hey April..."

April could immediately tell from his tone that something was wrong.

"Donnie! What's going on?" It was nearly midnight, and the T-Phone had woken her up. She sat up in bed, ready to get dressed and head out if needed.

He responded quickly, trying to reassure her, as he so often did. "No, no, it's okay. Nothing's...nothing's wrong." A pause. "I guess it's - oh! It's kinda late. I'm sorry, I wasn't thinking, April."

His tone was despondent. April's brief flash of anger at his admission that there was supposedly nothing urgent turned quickly to concern.

"Donnie. You should be asleep. You're seriously injured!" She sighed, voice softening. "But, since we're already talking...what's going on?"

"Well, the thing is, I-I-I have this weird question, I mean, sort of a hypothetical scenario. Kind of a, kind of a- a theory, in fact, it's not, you know, based on anything real..."

"Donnie." April cut him off, voice firm. She had never heard him this scattered before. "Just breathe. And rela-ax. Okay? I'm listening." She let herself lean back into her pillow.

A sigh came through the line. "April, what if you found out you weren't related to your dad?" There was a pause, as April's eyes went wide. "I mean, you are. But, what if, in a hypothetical scenario, you found out you were adopted?"

"Donnie, what is this about?" She sat up again, his words having hit an unconscious panic button in her mind. These days, the topic of her father tended to have that effect. But it was the strange timbre she heard in Donnie's voice that had her sitting back up, reconsidering the need to get dressed.

He just sounded so completely unhappy.

April pressed on when the line remained silent, surprised that she was the one reassuring him for once, and finding that she was eager to fill that role for him. Her voice came soft, and full of warmth. "I'm here for you. And I don't need a what-if scenario. Just, tell me what's going on, okay?"

"It's...complicated."

April smiled gently. "With you, it always is."

Donatello snorted, and April knew she'd cheered him up a little, but the line still remained silent for several seconds before he continued.

"I've been keeping something a secret." There was another long pause. "You know how...how Splinter was my donor."

It was a statement more than a question, and his voice sounded depressed now, causing April to unconsciously grasp the T-Phone tighter. She made herself smile, to keep her own voice light, hiding her worry for him. "Yeah?"

"He kind of noticed. Of course. I mean- I mean he asked why."

"Asked why..."

"Why it couldn't be any of the others." There was another sigh, which was probably some kind of record for Donnie. "So...this is where it gets complicated."

April's smile dropped, heart clenching at the pain in his voice. Donnie never had trouble explaining things, even when those things weren't pretty. Yet he'd kept this thing, that had something to do with his family, with their blood, a secret for who knew how long.

April closed her eyes, wishing she were there with him to give him a hug. "Donnie, it's okay. Whatever it is you need to say...it's okay."

I'm your friend. I'm here for you. But that's what she'd tell Irma, maybe, and those words weren't enough. Different words started spilling out, as she tried to comfort him.

"You...you saved my life. You found a way to turn my dad back from a mutant bat into a thinking, feeling human being again. Donnie. You...are one of the most caring, amazing people, and, and a few days ago, when you got shot..." April had to stop suddenly, as emotion overwhelmed her. She hadn't meant to go there, but the shock from a few days ago was suddenly back; that feeling of horror, as she'd struggled to stop Donnie's collapse to the concrete.

April pressed her lips together until they turned white from the pressure. Then she made herself keep going, because she had so much more to say, but her voice was faltering and only grew weaker as she spoke.

"I don't know why...what I did to deserve having a person like you in my life, but I try to think that maybe, if the time came, I could be like you...that I would be w-willing to die for the people who matter, Donnie. B-because you do that, and k-keep doing it, and honestly...I'm not s-sure I'm worth..."

"You are. You absolutely are, April." Her warm, confident Donnie was back, and she knew he didn't doubt his words for an instant, even while assuring her she was worth dying for. And he was still telling her this, even after how close they'd come...

"I almost got you killed...!" The words hardly had tone as she choked them out. April put a hand over her mouth, suppressing a violent inhalation as tears ran down her face.

"No...no. I'm fine. I'll be okay. I'm here. Don't cry, April. Please."

"D-Donnie..." She huffed and wiped her runny nose, throat working against her.

"I'll be at 100% in no time at all! You'll see..." He dropped off, surely trying to think of something to say. April shook her head, unable to express why his words didn't make up for that night. She tried to get herself under control again, amazed and embarrassed that she had fallen apart like this, when the goal had been to comfort him, to be there for him.

That brought the flood to a stop, as righteous anger, self directed, took control.

April clenched the phone to her cheek, her words, rough but under control again, coming out with the intensity of a fervent prayer. "I promise I'm going to work my butt off to be the best kunoichi ever, Donnie. Because this is not okay! You taking a bullet because I couldn't hold my own is not okay. And it's not going to happen again. I will take a bullet for you, before I let this happen again."

April sniffled loudly, once, and wiped her nose, the tears finally banished as determination took their place. She swept the palm of her free hand over her cheeks, leaving a gentle burn in their place.

She cleared her throat, and neither spoke for a long moment, as her breathing stabilized. She blew out a long, calming stream of air, and sat up straighter. "So. Anyway. You had something you were trying to tell me. About Splinter."

"Right." Donnie paused. "April..."

"Yep?" She bit her upper lip, focused on his voice, almost comically so, determined that she was going to comfort him, and be his listening ear.

"Thanks."

With the touch of that one gentle word, the manic glint left April's eyes, and her entire frame softened. She huffed gently, her lips quirking into a lopsided smile. "I mean what I said."

"I know you do." Donnie finally sounded happy again, almost playful. "But, I don't want you getting shot either..."

April cut him off, jaw firm. "No one is getting shot. They won't even see us, let alone get a chance to shoot."

"Because we'll just be that good." His voice was light.

"Yes, we will." April huffed out a gentle laugh. "I'm serious, Donnie."

"I know. I am too." He sounded way too happy to be totally serious, but she let it slide. He wasn't so horribly sad anymore, and that made everything better, brighter, again. And also, this was something they could do. They would train, and plan, and prepare...

April was going to have to knock some caution into Mikey's thick skull, but they'd get there. She would make certain.

But right now, she was going to be there for Donnie. "So. Splinter." April let out a long, silent sigh, the stress she'd released over the last few minutes almost tangibly slipping away from her frame. She felt centered, and ready to listen.

"You know what? It doesn't matter." Donnie sounded calm.

April frowned, slightly taken aback. "Are you sure? You called me at midnight, sounding really upset, Don."

There was a brief pause. "We're family. Right? I mean, what is genetic code? The people in your life who are there for you, the people who raise you...that's what counts."

April nodded. "Right." Splinter and the turtles were family, without a doubt.

"So, the thing I was going to tell you? It doesn't matter." She could sense Donnie's smile. "Thanks, April."

She chuckled, still overjoyed that he was feeling better, and happy that she had somehow helped, but she was also, admittedly, vaguely curious. "You're...welcome?"

Donnie chuckled too, then pulled up short, and a pang went through April because she knew it was his shoulder hurting him.

His voice, still happy but slightly more tense, confirmed it. "Hey, I should let you get back to sleep. I woke you up, didn't I?"

April looked at her bedroom window, picturing him perched there, his lanky form taking up the entire sill, his large brown eyes shy, but warm.

Her face melted in to a gentle smile. "Maybe."

"Oh man, I'm sorry A..."

"Donnie, it's okay. If you need to talk, I'm here for you. Any time, I'm here."

"Thanks, April." Her Donnie, in the window, bowed his head slightly, smiling that rare, guileless smile that made him look about ten years old.

April leaned into her T-Phone, and knew that smile really was on his face right now. "Good Night, Donnie." Her brow furrowed slightly. "And get some sleep, you're healing..."

A gentle huff. "I will, I promise. Good Night, April."

After Donatello hung up, April snuggled back into her pillow, getting comfortable again. Then, still holding the T-Phone, she drew both hands to her chest, nestling the phone close to her heart, and fell back asleep.

Splinter came to sit with Donnie on the couch the next evening, shortly after the others left to patrol. Due to his injury, Donnie wouldn't be joining them again for many weeks.

He had brought the tea set. Donatello honestly couldn't remember a time it had been used outside of Splinter's own room. He watched, uncertain, as Splinter went about preparing the traditional drink.

Even after the talk with April, it was one thing to come to terms with explaining things to his father, and another to actually do it.

"Sensei..."

"Here, Donatello. Drink." Donnie set down the TV remote, the television itself already off, and took the proffered cup carefully in one hand.

They sipped tea for a few minutes, making time for a comfortable, familiar silence to build between them. This was his father, his sensei; the person who had raised him from infancy. The person who had named him, and helped him take his first steps. Splinter knew him in a way no one else did. Donatello had time to think these thoughts, and to appreciate that Splinter had moved the conversation to the living area for him, because of his injury.

When the tiny cups were sitting with the set once more, Splinter spoke again.

"Something has been troubling you, my son. Something about your transfusion." He bowed his head, eyes closing briefly, then looked up, into Donatello's eyes. "I do not wish to pressure you. But if there is anything you wish to say, I am here to listen."

Splinter's gaze, although concerned, held no pressure, reflecting the truth in his words. Donatello knew he'd been nothing but tension and nerves around him for days now. After realizing what incredible stress this secret he'd held onto had caused, when nearly discovered, he couldn't help feel relief at Splinter's reaction.

It was tempting, to tell him that, no, in fact, there wasn't anything he wanted to say. Donnie's hand physically ached for a moment, as he fought back the powerful urge to pick up the television remote, and casually flick on anything at all, to create some kind of distraction. Yet after surely causing Splinter to worry, Donnie knew he owed his sensei an explanation. He reminded himself, firmly, that they were all family, that nothing could change that.

Trying to grasp some of the peace he'd felt last night, after talking with April, Donnie tried to make a start. "When I was...when I was twelve, I got fascinated with genetics. I don't know if you remember..."

Splinter smiled wryly. "Indeed I do. I believe that was when you finally got your lab, and the rest of us could be safe knowing the items in the refrigerator would not cause death if consumed."

Donatello grinned sheepishly. "Yeah, I think Mikey particularly benefited from that..." He cleared his throat, feeling awkward for a moment. There had been a few...incidents.

"I- I didn't have a lot of genetic material to work with, and so...maybe naturally, I focused on us. Remember, that's when I started patching everybody up? I'd get out my little medical kit, the gauze...and well, I kept some samples. I think it took me a few months to get everybody."

Splinter crossed his arms, tucking his hands into his sleeves, his voice warm. "Yes, I do remember. You have always been very meticulous."

Donnie grinned, remembering back for a moment. "You were trickiest, Sensei. I didn't think you'd ever get a cut!"

Splinter chuckled. "And you were so eager to treat my tiny wound! I think I was slicing an apple?"

"Yeah! And you were having raisins on the side, and a little lump of that smelly cheese nobody else would touch..." Donnie dropped off, grin faltering. He knew his memory made others uncomfortable sometimes, and from the brief flicker of uncertainty in Splinter's eyes, he'd given more detail than his sensei could recall.

Splinter picked up the conversation, gently leading. "And so, being curious, you ran some tests."

Donnie nodded. This was it. "Yes, Sensei. I...I found out that...Leo, Raph, and Mikey, they...they're, well, biologically speaking, they're full brothers. And I'm...not. I share DNA with them too...but I'd be more like a first cousin to them. A half brother, at most. And, I also found out that..." Donnie dropped his gaze, staring down at his knees. "I share DNA with you, Sensei. About...about fifty percent, actually."

Donnie's face grew hot. He felt exposed. It felt wrong to share this, after so long. He'd decided, at the age of twelve, that he never would. But here he was, breaking that promise to himself.

He continued, still staring at his knees, trying not to stutter, strangely compelled to give more detail, now that he'd said it out. "When I got the chance to study mutagen, it started to make more sense. You see, y-you must've touched me, before the mutation. But, the others must have come into contact with someone else, probably someone working at the pet store."

Donnie fidgeted nervously, his words picking up more speed. "That would explain a few things, like our builds; you're unusually tall for a Japanese man, and I'm the lankiest of us four...and our eye color, too; I think it's likely they share their human DNA with someone of European descent. So, that's why you and I are donors to each other, while they're donor's for each other. A-actually, I wasn't totally sure, if your blood would take, to be honest, although, don't get me wrong, I was reasonably confident, very confident, in fact. But I knew I didn't stand a chance with them. It's difficult to explain, but our blood itself- Raph's, Leo's, Mikey's, and mine- the structure is almost entirely human. W-we're all a mix between human and turtle, obviously, but the turtle genes display in different ways; actually, in a sense we share similarities to the chimeras that rarely occur in nature, although that's- that term doesn't explain us either, I mean, come on, we were exposed to mutagen from Dimension X as infants, of course it doesn't really apply, but for conversation's sake...Um, but anyway, our blood itself wouldn't pass muster as human, per se, but in regard to donor compatibility, the human blood typing system roughly applies, and I would lay money on the fact that the pet store employee who influenced their mutations had type A blood, because Raph, Mikey and Leo are all type A...well, close enough for the categorization to hold merit, anyway...while you and I, for the record, are type B; again, sort of, I mean our blood isn't even fully human..."

At this point, Donnie was talking a mile a minute. "Oh! And I misspoke earlier, because when I said I share about fifty percent of your DNA, I meant your human DNA, pre-mutation, so, heh, as weird as it is, n-now that I think about it, that would mean Karai- um, I mean, Miwa - is kind of like a-a half sister to me. Heh, wouldn't that be an interesting conversation; hey Karai, guess what? We're related! Yeah, my skin's green and I have a shell and three fingers, but you're actually in all probability my closest blood relative..."

Donnie knew he was rambling, but it was like his mouth took time to catch up to his brain. With the last comment, he just stopped, jaw slightly slack, breathing a little harder than normal, silently panicking at all the things he'd just, just...spewed. His heart was starting to hammer in his chest, the wound in his shoulder throbbing right along with it. And though Donnie knew he should stop, it was like he'd sprung a leak, because words started pouring out again.

"Not that it matters, beyond how it can be applied medically, of course. I mean, Raph, Leo, Mikey; they're my brothers, you're our father, we're a family...April's family now, too. She made me realize that. This is just DNA; it doesn't define us. It shouldn't matter who's biologically related to who, it doesn't change anything. We're all a family."

Donnie stopped again. He was repeating himself. He knew he sounded desperate. And his shoulder was fiery agony at this point, but he couldn't relax to ease it, couldn't lean back, or look up, or do anything, except sit there. He knew what he'd said was true, he knew it, but...

"All this time, you've kept this to yourself. Since you were twelve years old..."

Donnie froze, even his breath pausing for a moment. Splinter's tone was soft, but an overwhelming fear suddenly prevented Donnie from raising his eyes, to see what might be there waiting for him.

He forced himself to answer, head bowing guiltily, as if confessing to something. "Yes."

Donnie started when Splinter slid across the couch. His eyes went wide as his sensei gently enfolded him in a hug. Donatello sat, still frozen, shuddering ever so slightly. He was distantly ashamed when a childish sniffle escaped. He was crying, like a little kid, and he wasn't even sure why.

Splinter sighed quietly to himself, as he held Donatello. It hurt his heart, to hear his quiet, contained sobs, brought on by the fear of rejection, the fear of losing the very thing he claimed wasn't effected by his discovery; his family.

Splinter wondered what other secrets he might have hidden away. The most secretive, the most intelligent of his children, he realized now, had become skilled at a very young age at wearing a mask to hide things away.

Yet, in some ways, he was easy to read. His crush on April O'Neil, his fascination with technology, his disgust over Michelangelo's pizza toppings. But Donatello possessed the ability to hide away bigger things, emotional things, to keep them buried deep under...a skill that was very useful to the ninja. He could have excelled at espionage, had he been fully human. But that talent was a dangerous one. Yoshi had seen people destroyed by their inner demons, taking their pain to their graves.

He exhaled a calming breath, and pushed those memories away. His sons were not fully a part of that world, and part of him was thankful for that.

"My child, there is no need to keep secrets from me. I am here, as your Sensei, and father to you all." He gently pulled back, and Donatello, eyes bright with tears, finally met his gaze. "You suffered, keeping this to yourself, my son. Please know that I will never judge you. Know that I love you. I want you to come to me, to share. Especially when you think you have something you must not share, when you think you must protect others from the knowledge, that is when you must share. Do not keep it inside. Promise me, Donatello."

Splinter saw him hesitate. "Share, if not with me, then with someone else. Will you promise me that?"

With that, Donatello relaxed. "Hai, Sensei."

"And you are right, of course." Splinter smiled softly, and waited for Donatello to catch up.

"Oh...oh! Of course." Donnie smiled back.

"What is that song? Your brother sings it sometimes..." Splinter tried to sing a few phrases. "We are fa-mi-ly. I've got all of my sisters with me..."

"Sensei, stop, not you too..."

Splinter chuckled quietly.

In the end, Donatello gave some mumbo jumbo commentary about the unpredictability of mutagen, and its inherent instability, and handed Leo a simple chart showing who could be a donor to who. Leonardo hardly batted an eye, and went to place it in a drawer in his room along with other things he'd deemed important to keep track of over the years.

April, Donnie could tell, read into the chart more. She was in the lab at the time, listening as he had rattled off the explanation to Leo. After their talk the other night, the knowing look in April's eyes was hardly surprising. Also, she knew more about genetics than his brothers, who, thankfully, had absolutely no interest in the subject.

If April had drawn the right conclusion, though, she didn't share it with him. Instead, she had found a new focus.

"Listen, guys, this is perfectly reasonable! People wear clothing. Armor is..is kind of like clothing! I mean, you walk around with your arms and legs and everything totally exposed." She crossed her arms. "I'm embarrassed, actually!"

Raph raised an eyebrow at that, from over by the punching bag.

April's cheeks colored slightly. "Okay, no, I'm not really...just forget I said that. But you guys can wear pants...Kevlar pants! You'll get used to it, trust me. And some kind of upper body protection! It just makes sense. Hey, you'd like to wear a cape, right Mikey? Donnie! You're on board, right? Let's make you guys armored clothing!"

~End~

Author's Note: Well, that's that! This story began as a means to write out this theory. As a result, I think I could've fleshed things out more, but it ultimately served its original purpose of sharing my thoughts, and also allowed me to try my hand at writing these characters. There's so much there; each personality is distinctly formed, and that's something most fandoms just don't have to this extent. It's a wonderful thing, but kind of...daunting, as well? Anyway, I hope I did them justice! (As with the prior chapter, constructive criticism is welcomed!)

On a separate note, a big part of me really doesn't like the idea of only one turtle being related to Splinter, etc, because I think one of the biggest strengths of TMNT is their bond as brothers, and their genes can just go hang themselves. But, at least in the newest series, their character designs seem to lend themselves toward this idea. For me, anyway. Ahaha. Plus, the thought of Donnie explaining to Karai that they are biologically half siblings just really makes me laugh.

One last random thing: I think telling his brothers would be the most difficult for Donnie. As a twelve year old, that's what truly held him back; the fear of isolation from them. Splinter, I'm thinking, would be wise enough to realize that.