Full Summary:

If duty to his clan's ghosts didn't rest so heavy on his shoulders, Sasuke realised, he would be grabbing the nearest blade, pressing it to his own throat and— and then he was somewhere strange, somewhere new. Sat on a bench was a man with messy dark hair. Sasuke's heart lurched, but it was not another Uchiha. No Uchiha had vivid green eyes.

"I'm the immortal wizard," the man said. "And I have an offer for you."

Notes:

I wrote so much stuff in 2019 (110k words actually), most of which never got posted. This is another one of those – another "I envisioned it as the opening to a longer fic, but that never happened, so I've given it a vaguely open ending, and am now posting it as a one shot" fic. Will I post more of those? Who knows.

AO3 Tags: Uchiha Massacre, Tsukuyomi, Angst, Consequences, Implied/Referenced Suicide, AKA: Why Torturing Small Children Is a Bad Idea Itachi You Idiot, Master of Death Harry Potter, Immortality, Reincarnation, One Shot

An Offer, an Ending, a Beginning

Sasuke gave up. Somewhere around the fiftieth time he watched his beloved brother cut down every other person he cared for – even their own parents – Sasuke's will just… broke. And he knew he'd never be whole again. If duty to his clan's ghosts didn't rest so heavy on his shoulders, Sasuke realised, he would be grabbing the nearest blade, pressing it to his own throat and—

Suddenly, the clan compound was gone. There was no eerie bloodied moon above. No screams or sword or corpses.

He was somewhere strange. A long public hall of sorts. It was pale and white, with pure sunlight glittering through the glass ceiling above. There were brick walls, and down the middle was a deep, sunken section with parallel metal lines set in the ground, crossed with wooden planks like a ladder laid flat. It niggled at a memory. A mission Shisui mentioned once. Something to do with Land of Snow?

Not that it mattered. Shisui was dead. He had probably, in hindsight, been the first victim of—

"Where am I?" he rasped.

"King's Cross Station."

Sasuke whipped around, eyes wide and shamefully frightened. He relaxed when he saw it wasn't—wasn't him.

Sat on a bench was a man, tall and pale with messy dark hair. Sasuke's heart lurched as he at first, irrationally, thought it was another Uchiha, another survivor. But no, no Uchiha had anything but dark eyes, and certainly not such a bright, vivid green. This man was a stranger. Sasuke would have remembered meeting someone with a lightning jutsu scar on his face.

The man yawned, running a hand through his hair in an utterly failed effort to bring it to order. He patted his clothes then pulled out a pair of round glasses, setting them on his nose. He blinked a few times, as if waking up properly, then looked at Sasuke with deeply sad eyes. "So young," he murmured. "I am so sorry for what you've gone through."

Sasuke shied away from that. "Who are you?"

"My name is Harry. And you?"

"Sasuke. Sasuke Uchiha. Where is this King's Cross Station? How did I get here? Are you working with my bro—" His mouth snapped shut so hard his teeth clacked. He couldn't call Itachi 'brother' anymore. Not after what he'd done. He couldn't. So he settled on a glare and, "That man?" instead.

The stranger shrugged. "I have no idea who you're talking about." Then he sighed, long and heartfelt. "You're here because it was too much."

Sasuke flinched. "You know…"

"None of the specifics. It's like this, Sasuke: Once upon a time, there lived a wizard. He just wanted to be a normal boy, but fate had other plans for him. One day, he accidentally united some powerful magical artefacts and became immortal. He watched his friends and family grow old and die around him: his wife, his children, his grandchildren," Harry said, voice strained with grief. "He couldn't do it. Not forever. So he found a way out." Green eyes pinned Sasuke in place with an attentive gaze. "What do you know about reincarnation?"

"The… recycling of chakra?" Sasuke said, remembering a children's book his mother once read to him, when he was very small, about the Sage of Six Paths' sons. Truthfully, he was glad for the distraction of this man and his strange story. He didn't want to think about… that. Not yet.

He didn't have the strength.

Harry frowned. "Um. No? Or maybe? I'm not sure what chakra is."

Sasuke gave an incredulous look. "Chakra is the basic energy of life. It's all around us. It makes jutsu work!"

"Oh! Like magic. No, I'm not talking about the, er, recycling of chakra, but rather of souls – a person who dies, and then is reborn as someone else."

Sasuke crossed his arms. "I've never heard of that."

"Well, it's a thing. A thing the immortal wizard arranged for himself, hoping it would help make immortality less wearying. Only, he didn't really think it through. Bit of a bad habit of his," Harry said wryly, "rushing forward, not thinking things through. The reincarnations tossed his soul through different times and dimensions, and constantly losing his whole world at the end of every life was just as terrible as what he'd tried to escape. Still an endless string of loss. So the immortal wizard decided it would be better to forget."

"Forget?" It was an interesting story. Without realising, Sasuke had stepped closer and taken a seat at the other end of the bench.

"Forget. With every rebirth, the slate was wiped clean, as it were. When he was reborn, it was as an ignorant, innocent baby in mind, not just body. And so he kept living lives, all unknowing… unless certain circumstances were met." And here, his gaze fell heavily on Sasuke. "Sometimes, terrible things would happen to him, and his current incarnation would… break. But more than that, they were trapped. They couldn't just die – duty or vows or some other responsibility held them back from that mercy."

Sasuke swallowed hard and looked away. He pulled his feet up onto the bench, wrapping arms around his shins. He thought of his bro— of that man. He thought of losing everything that mattered. And then he thought how he couldn't die and join his parents and clan like he longed to, not yet. Not until he'd avenged them so their spirits could rest in peace.

Could it be…?

"Sasuke?"

"Are you saying I'm the immortal wizard?" He glared. "There's no such thing!"

"Yes and no. You're just a boy. You don't remember any of that. But me?" The stranger tilted his head, then pulled a knobbly stick from one sleeve. He waved it and an ephemeral, glowing white stag appeared.

Sasuke's breath caught as it brushed by him, emanating a sense of… of peace, which he'd thought he'd never feel again.

"Me?" Harry repeated as the animal faded. "I'm the immortal wizard. And I have an offer for you."

"…I'll listen."

Harry blinked his eyes open. Above was a white ceiling. The air smelled faintly of lemony cleaner and antiseptic.

He knew a hospital when he woke up in one.

He stretched, and sighed in pleasure at the novelty. He'd been asleep for a long time, quiet and still and ignorant but for the occasional passing dream of the outside world. It had been hundreds of lives since the last time something had gone so catastrophically wrong as to awaken him.

He grimaced at the reminder. He couldn't really enjoy this, not knowing what had broken Sasuke. He closed his eyes again. Merlin, but his latest incarnation had been so young. Just eight years old.

The worst part was that his older brother, the engineer of his suffering, was just a boy himself. Maybe the original Sasuke hadn't seen it that way – Harry felt some lingering admiration and awe for his 'grown up ninja' older brother, albeit stained with betrayal now – but Harry was an actual adult. He'd been a father once upon a time, and he could see things a bit clearer.

Itachi was only thirteen. He had been as much a child as Sasuke. But their parents, their clan, the elders… none of them cared. They pushed and pushed, too far and too soon, always demanding more so they could bathe in the reflected limelight of Itachi's prodigious achievements.

And, like Sasuke, Itachi broke.

It was a tragedy in every aspect. There was no clear-cut villain here. Harry would kill Itachi as he'd promised Sasuke, so that their clan's spirits could rest in peace. But he'd do it as much for Itachi as he would Sasuke, because the reordering of their mind, the assimilation of old and new memories, had broken that little genjutsu-style Obliviate Itachi put on him. Harry remembered the tears in their older brother's eyes as he turned away from their parents' corpses. He remembered the guilt.

Killing Itachi would be a mercy to the older boy. A kindness.

Just like allowing Sasuke's spirit to move on while Harry took over his life had likewise been a mercy.

Harry sighed sadly. A glance out the window showed it was nighttime. He would get some sleep and deal with things in the morning. Planning could wait till he'd escaped his hospital bed, which shouldn't be hard. Harry was well practiced in talking his way out of a healer's protective clutches. He didn't see why this time should be any different.

Harry might have forgotten one small, incredibly important detail.

In his defense, assimilating a whole other life's worth of memories was never an easy, straight-forward process.

Sasuke's body had been kept and cared for in Konoha's main hospital, in a bed in the most secure ward. Recovery from genjutsu torture was never a predictable thing – least of all Sharingan genjutsu – so no one was surprised that it took time. As hours turned into days however, and days neared a full week, people started to worry. What if the poor boy never woke up?

The morning Sasuke's medic found him awake was, understandably, met with much relief.

Relief quickly turned to shock and confusion, then slowly dawning horror, and finally twisted into accusations thrown at everyone who had had access to the boy, because…

His eyes were green.

The End

Notes:

Harry is like "oops?". To be fair, a world with funky, magical, stealable eyeballs is a new one for him. At most he'd expected them to find the colour change baffling, not cause for alarm. And I think he still has the Sharingan – he's still bloodline Uchiha after all. The green is just an aesthetic "eyes are the windows to the soul" thing that carries over between lives.

Also, weirdly, despite me not being a fan of Sasuke or Itachi (especially Itachi), this fic is sympathetic to both of them. …I mean, aside from how they both end up dead?