Kakashi was four when he received his first mask. He didn't quite understand the importance of it but accepted the gift from his father who had slipped the small piece of fabric over his face and situated it over his mouth and nose, patted his head and told him to never take it off in public.

xxx

Kakashi was six when he learned what he was. His father had been dead for over a year now so Kakashi never got the whole bloodline speel and had to learn the hard way. He'd been badly injured on his first B rank mission. He was six and a Chunin, but his fellow Chunin teammates hadn't wanted to listen to him and the result ended with Kakashi as the only survivor and badly wounded. Instincts had kicked in and Kakashi had bitten the nearest source of blood.

xxx

Kakashi was fourteen when he died. It was the day of the Kyuubi attack and like the hundreds of Shinobi and civilian's Kakashi was just another tragedy. He was dead, his heart stopped and his body had gone cold. But when Tsunade leaned down to close his unseeing eyes, a drop of blood fell on his lips and like when he was six, instincts kicked in. He snatched Tsunade's wrist and took greedy gulps of blood.

"Tastes like dirt," Kakashi spat when he came back to himself and stared into Tsunade's shocked eyes. Kakashi was fourteen when he gave Tsunade a phobia for blood.

xxx

Kakashi was fifteen when he noticed he'd stopped growing. He'd stopped aging, and he'd only noticed because Gai's voice had stopped cracking every time he screamed of youth. Kakashi was thankful that his voice had matured when he was younger, but he was only fifteen and didn't fully understand how not aging could be a problem. Even so, he was a genius and began using Henge's in public.

xxx

Kakashi was eighteen when he learned how priceless his blood was. He was on a mission outside of the village and had bumped into Tsunade on his way back to Konoha. The moment Tsunade saw him, she dragged him to her hotel room and began rambling about something called, "Phoenix tears."

"I don't know what that is," Kakashi grumbled as the door slammed behind him.

"How can you not know what it is? Sakumo-"

"Is dead," Kakashi snapped before she could continue. "And what does Pheonix tears have to do with me or Him?"

He'd heard of Phoenix tears of course. It was some type of potion that could cure any poison and heal any wound. It was like Soldier Pills on steroids.

It was also a myth. There was no proof that such a medicine existed, and all the rumors about it were from the Shodaime's rein.

"Y-you…" Tsunade gaped but that soon turned into a glare as she tugged him further into the room. "Shizune was experimenting with poison. I'm not sure what type she was working on, she always keeps her experiments a secret from me, but her beaker exploded in her hand. I've taken out all the glass and drew out as much poison as I can but there's still some in her body. She's been running a fever since yesterday."

"Do you want me to run to the pharmacy?"

"No! Sit down!" She pushed him into a chair and with the elegance of a Sannin she sliced his wrist open and pushed a vial to it. Kakashi had no time to argue before she sealed the wound and pressed the vial - now filled with his blood into his hand. "Charge that."

"What?"

"Push your Chakra into it."

Kakashi glared at her. "No."

Tsunade snapped. "Listen child, my apprentice is dying and you're the only one that can save her. So you will push your Chakra into that vial, or her death is on you and I will kill you."

Kakashi's killed ton's of people, it comes with the job. He's also called Friend Killer for a reason, but this time there's no 'what if's,' there's just do's and don'ts, and this time there's a choice. He's never had a choice before, everything is by chance and even if Tsunade's spouting nonsense, Kakashi doesn't want another comrade's death over his head so Kakashi does.

He pushed his White Chakra through his arm, to his hand, and into the vial and like some light show, the blood within begins simmering and turning pink until it's white and glowing.

His blood is glowing!

Kakashi can't take his eye off the vial, not even when Tsunade plucks it from his grasp and pours half of it into Shizune's mouth.

"Pheonix Tears," She starts, "is blood willingly given by a Hatake."

It takes Kakashi a moment to process that he's the sole producer of Pheonix Tears and that if a vial of the Tears could buy him a small village, then all the blood in his body could buy out half of the Elemental Countries. But that's impossible, there's no way his blood is that priceless. There's no way that the glowing white concoction in Tsunade's hand could possibly be Pheonix Tears. If it was then he'd be under lock and key. The Hokage would never allow him out of his sights and Kakashi would probably be drained of blood on a daily basis.

If he's the sole producer of Pheonix Tears then what was the purpose of Obito pushing him out of the way? Why had Rin died if he could have healed her with a drop of his blood? Just. Why?

But instead of voicing this, Kakashi just crosses his arms and grumbles, "I didn't willingly give you my blood."

"But you charged it with your Chakra, that's all it takes. On the other hand, if your blood wasn't charged, wasn't willingly given, then we'd have Reaper's Tears. It's the best poison out there. Melt's the victim's insides and there's no cure. Not even Chakra can stop it fast enough."

"It's a fair trade off don't you think? You can regenerate yourself as long as you have a human source of blood, and with your Pheonix tear's you can heal us from near death. Just don't tell anyone or you might end up as someone's lab experiment. Not even Sensei knows."

Kakashi is eighteen when he throws himself into Anbu with no care for his life and too much for his comrades. No one dies on his watch, and by the time he's nineteen he's lost count of how many times his heart has stopped and he's woken up by himself and a long journey home.

xxx

Kakashi didn't think, his body just moved of its own accord and jumped in front of the ballistic Jutsu. Hands outstretched, Kakashi did his best to block out the electric onslaught but he could feel his gloves disintegrating into dust and the bite of burns arcing into his skin as his shirt was shredded into pieces.

When the attack ended, Kakashi allowed himself a moment to gather himself and assess the damage. His gloves were nonexistent, same for his vest and undershirt, and though his chain mesh and pants had survived, his pants were barely hanging on by a thread and had burnt edges.

Bringing a hand to his face when a small gust of wind brushed against his bare cheek, Kakashi growled, "you're going to-" He grunted when a fist buried itself in his stomach and his Henge dispersed.

The shock that echoed within the clearing was nearly tangible and Kakashi could practically feel the questioning glances from the Ino-Shika-Chou trio and the amused looks of the Akatsuki.

He flipped away from Hidan, the fact that his blood coated Hidan's knuckle wasn't lost on him.

"Now you're really going to regret that," Kakashi said, wiping the blood from his mouth as he watched Hidan lick the blood on his knuckles.

"You know," Kakashi began as Hidan began drawing his ritual circle, and ignored the way Asuma's students began a frenzied rush toward the man. "I've always wondered what the blood of my enemies taste like and how I'd fare against a fellow immortal."

The shocked look on Hidan's face was laughable.

"And I wonder how a fellow immortal would fair against Reapers Curse. I mean the grim reaper is known for hunting down people who try to avoid death."

"What?"

Kakashi grinned and darted for the skeleton tattooed man before jumping over his head and latching onto Hidan's back.

"Your injuries get mirrored onto me, right?" Kakashi asked rhetorically but didn't waste a second longer before sinking his fangs into Hidan's shoulder.

He could feel the burn of a bite mark on his own shoulder and the small trickle of blood that dribbled onto his chest, but Kakashi could feel it healing with each gulp of blood he took, and he didn't feel like he'd just spilt a gallon of blood which was about the amount that Kakashi had sucked out of Hidan.

It was sort of a surreal experience. Kakashi had never fought like a hungry beast. He'd always fought like a Shinobi. With flashy Jutsu when he needed to be obnoxious, and stealth when he needed to lurk in the shadows. He'd fought for his life and his comrades lives, but had never drank the blood of his enemies despite knowing what type of boost it could give him.

The strength that flowed through his veins felt astronomical like nothing could stop him. Even the chakra drain that his Sharingan caused, felt like a small trickle compared to the rampaging rivers that were now his chakra coils.

It felt amazing.

Kakashi sucked harder when his torso mimicked the slice that stabbed through Hidan's stomach and out the back. He even felt the scythe graze his chest before Hidan pulled it out and went for it again. But even as the wounds littered his body and his hand got severed, Kakashi could feel himself healing.

He could feel his muscles pull themselves back together and force his bones to align as the skin on his stomach stitched up, and he could feel threads of his Chakra, still attached to his severed hand rope themselves to his stump of a wrist and pull and tug until his hand was situated where it should be, and heal.

Kakashi felt unstoppable but he wasn't suicidal and so even though he was certain that he could reattach limbs and heal from wounds to the torso, Kakashi wasn't willing to test if he could handle being speared in the heart or being beheaded.

Hey, he didn't only read Icha Icha. Some of his library consisted of the supernatural with Vampires and Werewolves and such.

So when Hidan's scythe aimed for his jugular, Kakashi caught the blade in his hand and squeezed. He could feel his skin cutting even as it healed, and could feel the way the metal bent in his fist.

"Mah, thanks for the meal," Kakashi said as he wretched the scythe from Hidan's grip and flung it away from them.

"Y-you," Hidan gasped. "What are you."

"Who knows."

"You mother fucker!"

Kakashi clucked his tongue. "Oi, there's kids over there! Watch your language!" The irony of his statement wasn't lost on him. He was well aware that without his Henge he looked younger than the Ino-Shika-Chou trio.

Whatever. He was still older.

"I'm gonna kill you!" Hidan ranted.

"Very unlikely. Though I am surprised you're still alive."

"Fuck you!"

"Language," Kakashi reminded. "So how's it feel like to have your organs eaten from the inside ou-"

Kakashi was forced to leap away from Kakuzu and noted the porcelain mask that was sewed to his chest. The painting marked it as a lightning heart.

The only element Kakashi had barely any control over was wind, and it was that very element that he needed to take out this last heart.

Kakashi wanted to call foul.

But he was thinking like a Shinobi again, and not like a vampire.

Kakashi quickly glanced at Hidan, noting how the skeletal tattoos had faded and how his entire body looked like one huge bruise. Once Reaper's Tears ate the organs it'd go for the muscles, then the bones and finally the skin, leaving only the blood of the victim. Kakashi wasn't sure how immortal Hidan was, if he didn't age, or simply couldn't die from traumatic wounds, but even if the man didn't die, Kakashi was sure that he wouldn't be able to do any damage if he was only a puddle of blood.

And if one immortal could be taken care of with Reaper's Tears, then what's to say that another couldn't? True, Kakashi had no way of penetrating the shield around the lightning heart, but it was just a heart. An organ. And the body was made up of threads which absorbed liquids right?

Right.

So all he had to do was spill a bit of blood on the thing and let threads do all the work… Right?

Of course things were never quite so simple, so even though Kakashi managed to get blood on Kakuzu, and could see it eating away at his skin and spreading along the threads, it wasn't working as fast as Kakashi wanted to, and the mere act of getting blood on the man had put Kakashi in a vulnerable position.

Really, he should have thought it through better.

"I could make a lot of money off you," Kakuzu said. His threads latching onto Kakashi and holding him still.

xxxxxx

When Sakura arrived at the scene, she had expected many things, but she hadn't expected the fight to be over yet.

Ino was by her teammates, and although they looked relatively unharmed they still looked like they'd just been forced to learn some life changing fact and none of them could take their eyes off the crouched figure of what could only be a fourteen year old boy.

Landing next to her friends, Sakura shared brief nods with them, but from Shikamaru's contemplative look, Chouji's horror stricken face and Ino's kinda sorta "oh that's cute but kinda disturbing" look, Sakura turned to the crouching boy and the sprawled form of their enemy across the field.

"Who-"

"That's Kakashi-Sensei," Shikamaru said.

Sakura blinked, not believing the Nara but not able to laugh at his obvious joke either. Shikamaru rarely told jokes, especially not jokes about his fellow Shinobi.

Taking in the boy, Sakura noted the bloodstained hair and how he seemed focused on the body at his feet. It reminded her of the times Naruto had been taken over by the nine tails.

Sakura took a step forward and raised a brow when the boy took a defensive pose over the body and growled.

Taking another step, Sakura didn't pause in her walk across the field until she was five feet away from the boy. It was obvious now that Shikamaru was right. She wasn't sure how it was possible, but from this close distance, Sakura could see the scar that spanned over his left eye and the Sharingan.

"Sensei?"

He growled, low and guttural, hackles raised.

His entire posture screamed at her to back off, but he didn't look like he was about to attack her.

"It's me, Sakura," she spoke calmly as she crouched to be at eye level with his bloodied face.

It was her first time seeing him without his mask or this… young looking. She'd have to ask about that later.

Suddenly the body, which upon looking closer - was not dead, moved and thin threads snaked toward Kakashi and pierced through skin before Kakashi growled and burst into white Chakra. The threads withered and like the cat who caught the canary, Kakashi leaned back onto his haunches and licked his bloodied hands clean and almost like magic the wound's he just got, healed.

"Kakashi?" Sakura asked, looking for any form of recognition but Kakashi barely glanced at her, more interested in the body of the Akatsuki. "Kakashi," She said again, this time edging closer and placing a hand on his shoulder.

He flinched, looking ready to bolt, but when the body moved again he growled - not at her - and punched the man's head.

Sakura didn't know what to think. She'd never seen Kakashi like this before and while it didn't look like he was about to attack her, a small part of her was scared of him and remembering how Ino and her team had looked at him, it was clear that they were also scared of her Sensei.

Looking toward the body, Sakura barely recognized the face of the man she'd been given a brief rundown of. He was apparently immortal and had been alive since the Shoudaime's rein.

"Kakashi…" she said waiting for any reaction but not getting any, and continued, "you did a good job. Everyone's safe. You can stop now."

At the word "safe"he finally turned to her. Mismatched eyes looking at the hand she still had on his shoulder before looking at her face and tilting his head.

"Team 10 is safe," Sakura nodded toward her friends. "See? Kakuzu-" He growled "-Isn't going to hurt anyone anymore. You can relax now."

Sakura waited, watching how his shoulders relaxed and he sagged into himself as humanity leaked back into his eyes and she smiled at him when he glanced her way but quickly regretted it when he shrank away from her grip and skirted back.

"Sorry," he mumbled, chin tucked to his chest so that she couldn't see his face.

"What are you sorry for?" Sakura asked. If anything he should be proud. If Sakura was right then he'd single-handedly defeated two members of the Akatsuki with little to no help from the Ino-Shika-Chou team.

Kakashi shrugged, "you should tend to team 10."

"What about you?"

"I'm fine."

"Do you need anything?"

He shook his head.

"Not even a mask? The Kakashi I know would never go around without his mask," Sakura teased lightly as she fished around for her storage scroll. She nearly cheered when he glanced at her through a curtain of hair.

"You have one?"

"Yep, I always keep a change of clothes for all my boys," Sakura said, "but I'm afraid the clothes I have for you won't fit your current form."

"You bought an orange jumpsuit for Naruto?" Kakashi asked, now looking up, a small smile curling his lips and showing off a set of fangs.

"No, he left a set of clothes with me, just like you have in the past."

"From when you healed me," he nodded and Sakura could see he was starting to withdraw into himself again as he revealed, "if it's my clothes they'll have a seal on them that'll shrink to my size."

"Really?" Sakura asked, intrigued. For once the underneath the underneath message was clear. "So you're actually this short and normally wear a henge?"

"I'm not short," he grumbled. "I just don't age."

"You don't?"

He grunted and Sakura figured he didn't like where the conversation was going, so she shrugged and began unraveling her scroll.

"Here you go," Sakura said once she summoned his clothes.

"Thank you," Kakashi nodded. He'd just finished changing and pulling his mask up when Naruto jumped into the clearing and locked eyes with Kakashi.

What? Kaka-Sensei? What happened to you?"

"I got hit by a Genjutsu, it'll wear off," Kakashi said.

Naruto's grin turned into a smirk as he tried muffling his snickers. "You're so short!"

Sakura could see the irritated twitch of his eye and decided not to say anything. She could ask her questions later and perhaps direct them toward Tsunade. Kakashi had always been rather secretive.

A/N: What does Kakashi hide under his mask? Fangs, of course!

This plot bunny has cost me some sleep so I finally decided to put it on paper. It's pretty much just snippets, and any future chapters will probably be the same with no particular timeline.

Lemme know what you all think :)