Disclaimer

I don't own the Naruto Franchise, yet, but I'm working on it.

Zetsu watched from the forest as the silver haired boy's slipped easily through the girl—the Rin that Obito had obsessed over for the better part of a year—lightning crackling about his fingers as he watched as her consciousness slipped. The last thing spoken by her being the whispered word "Kakashi."

It was safe to assume that this was "Bakakashi."

The boy held her for a moment before letting her fall, either intentionally or not, and dropping to his knees soon after. He spoke her name, maybe to see if she would tell him that it was a joke or that she was still alive, before his teary eyes fell shut, as well. As soon as he fell onto the ground at her feet, and Obito shouted out, charging recklessly into battle with the shinobi who'd kidnapped her, Zetsu hopped from the branch and ran in.

He didn't know why he did it, perhaps it was just a moment of generosity while he was under the enormous disk that was the full moon, but rather than aiding the young Uchiha like he'd planned on doing, something willed him to do otherwise.

Sliding to a stop, he turned on his heel and ran toward the two young shinobi, scooping the girl up without thought and dashing back into the thicket of trees. He could hear the echoed shouts of the Mist shinobi, as well as those of Obito, even as he pumped an excess of chakra into his legs to speed himself up.

He didn't know where he was going, only that he needed to keep moving. And so he did, for what had to be the longest ten minutes he'd ever experienced, until he could feel his legs beneath him. He could tell that they were much weaker than they should have been, because he was trudging slowly through the tall grass which lined a path that had surely been stomped out by the hooves of countless horses pounding away there for years.

Lowering himself to his knees amidst the grass, and laying her down gently in front of him, he searched her only shortly before his eyes came to rest on the hole in her chest. He could feel her chakra coiling in the pit of her stomach, and a secondary, much stronger chakra alongside it, so he knew that she was still alive. Whatever it was inside of her, most likely a bijū, was keeping her alive. But it wouldn't be able to do it forever.

Normally, he couldn't care less about the death of a human. Though he didn't personally see all too many, he was aware of countless millions of deaths that had occurred in his nigh-century of life. He was one of about a dozen-thousand Zetsu Clones, and was linked to every other Zetsu. So, even if he weren't there to see very many people lose their lives, he had still lost all sensitivity to the prospect.

But, still... he couldn't help but to feel a gnawing sense of guilt at the thought of just letting her die.

Maybe he was going crazy? But, what Zetsu wasn't crazy?

Biting back his aversion to doing so, Zetsu gripped his wrist tightly and began to change the form of his hand. Over the course of a painful half-minute, he shifted his hand's structure, molding it to that of a heart. Still holding firmly the area that had been his wrist just a moment before, he carefully lowered the colourless, artificial heart into the girl's chest.

It took a minute of cautious mending, but he managed to connect the heart in the place of her lost one. He still had to pump it himself for a few minutes, her body not responding immediately to its presence after being void of a heart for so long. In doing so, he noted how much blood she'd lost, and against better judgment began to supplement bio-fluid from his own body to make up for the loss.

The rather painful ordeal took nearly an hour to finish, but after closing her wounds as seamlessly as he could, he sat back and watched her breath.

Zetsu spent a few hours monitoring her, making sure that everything in her body was still functioning with a steady, circuit-like flow of chakra between himself and her, flowing out of him and through her before returning and doing it all over again.

He felt... drained... for lack of a better word. That was worrying, but considering how much of his essence he'd just given to this human girl, it wasn't surprising. It was strange, the feeling of being tired, but also oddly comforting. He hadn't ever slept before, so it was startling when he was suddenly thrust into midday.

She was still lying on her back, sleeping but breathing quietly, very much alive.

The months he'd spent in Obito's company, watching the boy from afar rather than making himself know, had told him more about humans than the mostly distorted extra-personal memories about them offered. Namely, that they needed a constant supply of food and water.

He regretted severing his preferred, right hand when he started to pluck snowberries from the riverside shrubbery, where he'd carried her to. He lamented it more when attempting to scoop water into one hand. Though he wasn't interested in risking losing his left hand, too, he still crushed the white-blue berries in his hand, curling it into the form of a tube and drawing the cool water into a pocket in his lower forearm.

Returning to her, he eased the tube into her mouth, snaking it to the back of her throat before guiding it far enough down that it she wouldn't choke when he fed her. As he allowed the water and crushed berries to pour from the spout that was currently his hand, he silently hoped that she wouldn't bit it off.

But, she didn't.

He spent the entire day and much of that night, as well as vast portions of the following few days and nights feeding and monitoring her. He only had to redirect her waste once, and was thankful for it. He'd never understood why his counterparts, Tobi and Shiro more so than others, were so interested in poo, but he'd have to inform them that it should be avoided.

Her body, after the first few days, began to reject the artificial heart. He didn't have the take it out, thank the gods, but using his chakra to redirect many thousands, perhaps upwards of a quarter million, of her long dormant stem cells was almost as tiring as replacing her heart had been. He found himself thanking the gods for his hand's return, too.

The first healing period had changed something in him, and it went a bit further than him just worrying. Upon inspecting himself, he found that using all that chakra, and so much of his bio-mass to keep her alive, had changed his physiology. He grew tired, now, and had even experienced hunger for the first time on the sixth day. When resting on the sixth night, he'd also experienced what could only be described as a dream.

It was strange. Similar enough to the wisps of memories that he got from the other Zetsu Clones, but at the same time more... real? It felt like he was watching himself watch her, as she poked around a beach for hours collecting shells. It was silent save for her humming and singing, though he figured she could hear just fine, because after having filled both her pockets and all those on her apron with the shells, she spun her head toward the inner shore as if in response to her name being called.

He didn't know what they said, but he heard her clearly when she shouted "I'm coming" in response.

It was nearly a week after he'd saved her that she finally began to stir. He'd brought her beneath one of the larger trees in the area to shield her from the bane of the burning, summer sun. He was sitting back against said tree, peering through its countless leaves to the clear, blue sky when he noticed it, and so sat upright immediately. And he waited, for a few minutes.

Before, finally, she opened her eyes.