Sasuke wakes up with a thundering headache and a groan as his body's pain makes itself known. For a moment, he wants to block out the world, keep his eyes closed and pretend that nothing's happened. That his brother didn't go insane and kill their entire family, that he didn't see him kill their parents. That everyone isn't gone.
But his headache is bad enough that he knows he needs medicine and all he keeps thinking is I don't have a brother. For a moment, he wonders where Genos is, but then he wonders who Genos is and Sasuke (Saitama, his name is Saitama) can't make any sense of it.
He wrenches his eyes open and stares up at the white hospital ceiling. It's been years since he was injured enough to need to go to an hospital (but he broke his wrist two months ago training) and he wonders why he's there. Then he remembers his brother's Sharingan showing him the death of his parents over and over with a genjutsu (what is a genjutsu?) and he thinks the world doesn't make any sense anymore (when has it ever made sense?).
Sasuke scowls and presses the button to call for a nurse (medic-nin, not nurse) and he stubbornly ignores the pounding in his head as he tries to make sense of what his mind is telling him. Itachi-niisan killed their entire family and told him to hate him, told him that he needed to become stronger to kill him. That doesn't make any sense because Sasuke (Saitama) can remember killing things—monsters—with a single punch and he doesn't understand why he would need to be stronger. He knows he can kill his brother easily, even with chakra (what is chakra?) and he doesn't need to become stronger.
The nurse (medic-nin) comes in and gives him medicine for his headache when he asks for it. She looks at him with pity the entire time she's in his room and he ignores any attempt to get him to talk about what he's seen. Sasuke just looks out the window until she leaves the room then he look at his hands that are far too small (no they're not, he's eight) and scowls even more when he finds that he wants his big brother to explain this to him. Itachi would known what is happening, he knows, and Sasuke is to confused to be bothered that he's killed their whole clan. He wants to be mad and rage and hate his brother but he can't think like that. Saitama's (Sasuke's) feelings doesn't work like that. All he feel is a sense of loss and he once again wonders where Genos is when you need him.
But he doesn't know anyone named Genos.
Two weeks later, Sasuke leaves the hospital to go back to living in an empty compound filled with the ghosts of his clan (they're not his family, he doesn't have a clan). The world is still as confusing as it was when he woke up two weeks ago, but he's getting better. He knows that those memories, the ones that insists he doesn't have a brother, is from another life. He doesn't want to think about what that makes him, his life is his alone but sometimes things bleed through. When he first saw his reflection in the mirror, he was stunned to see he had hair, but he can't remember not having it.
Sometimes, the memories are strong and invasive and he can't recall who he is, other times it's like nothing's changed and he's still just Uchiha Sasuke. Except that he remembers being called Saitama-sensei and being a hero for fun. When he thinks of ninjas, he thinks of Sonic that declared himself his rival.
The main house in the Uchiha Compound stands empty when Sasuke enters it and as he makes his way to his room on the second floor, he resists the urge to run away from it and find his apartment (he doesn't have one) and instead lays down sullenly on the bed. He knows he is pouting and he knows he is far to old to do so, but the world is suddenly so very small. Worst of all, he misses his brother and Genos.
Sasuke can't recall who Genos is, and he knows there is no-one in Konoha with a name that strange, but he feels a sense of loss that somehow outweighs the loss of his family (they're not though) and again the thought that Itachi will know what's happening makes him scowl and frown at the white ceiling. He misses his family and his clan, but he misses his brother more and even Genos (who is Genos?) is somehow more important than his dead parents.
Sasuke settles into the routine of living on his own with the ease of someone who has done so for years, though he still feels strange when he's sitting down to eat, because he's not used to eating alone. Regardless, he does his best to look after the house, even if he locks his parents bedroom door and doesn't open it again. When he cleans his brothers room, he finds pictures of them together missing that he knows he saw the last time he entered, before his brother went insane and killed their clan. When he walks through his clan compound, he finds it strange that they're at the edge of Konoha, instead of further in because he knows the Uchiha helped build the village (his memories tell him it was deliberate, but he he's never thought of it before) and suddenly the tense dinners and sneaking around that the adults were doing has a whole new meaning.
(He wants to curse and rage at the world when he figures out why his picture is missing from his brothers room, it meant that Itachi didn't go insane, he meant to kill all those people. He meant to kill their parents.)
And then he goes back to the academy and the first thing to enter his mind is that they're even worse then Genos who was a cyborg (what is a cyborg?) and had no concept of self-preservation. They're kids, the other people in his class and that shouldn't surprise him because he has been in this class for almost a year, but it still does. They're all so small and breakable and Sasuke is afraid that just poking them will make them pop. His scores plummet in taijutsu because he doesn't fight back, he just lets them wear themselves out and gently trips them and sits on them until they give up and apparently he needs more killing intent if he wants to be a successful ninja and avenge his clan.
Sasuke doesn't know why he needs to avenge his clan, clearly they did something wrong if his brother had to kill them—because he knows his brother, he would only kill their family if it was the only choice he had—and so he just tunes the teachers out. The other kids in his class ignores him just as much as they stare at him and it's both annoying and frustrating in equal terms because he doesn't know why. Sasuke's scores on the written exams goes down just as much as the physical ones, because he doesn't care for it and only reads about the things that interest him. For example, the art of being able to seal things away in scrolls means not having to go home every time he tears his clothes and it's really a lot simpler then the teacher makes it out to be (Saitama kind of wants to hit them for not knowing what they're teaching but then remembers that he didn't really know what he tried to teach Genos either and so doesn't do anything) and he gets the hang of it fairly fast.
Sometimes, when Sasuke is sitting at home and just resting, he forgets where he is. It's not a conscious thing and he doesn't like it, but he does, because he is alone and has no-one to remind him of where he is and it just makes him determined to find his brother and get answers as to what happened. After all, he's pretty sure it's the result of his brother using the Sharingan on him that caused it, therefore Itachi should take some responsibly and talk to him.
Nonetheless, he can't tell people that because his teacher looked at him funny when he tried to explain it to her and he can't be bothered to put in more effort. If someone asks who he is, he might say Saitama depending on the day, but no-one ever does.
The first time he runs into another kid from his class outside of it is on a Wednesday that is unfairly sunny for his sour mood. Saitama (Sasuke) had spent the morning trying to work on his punch on the Uchiha's private training grounds, just to see if they were still effective and to his disbelief, they were. He was starting to think that his strength had less to do with his physical body's abilities, and more to do with just him. He'd thought that as he was in another world (at the start he hadn't been sure, but now Sasuke was certain his memories of this other life was from another world) but apparently that wasn't the case.
His punch was still as deadly as it had always been and Sasuke had almost had a mental breakdown right then and there if it weren't for the fact that the world he lived in now had chakra and shinobi and maybe, just maybe, there was someone out there he could go all out against. This thought is the only thing currently keeping him from breaking down into tears at the unfairness of it all.
Sasuke has only spoken to Nara Shikamaru twice, once to ask for a pencil and once to make him move over so he doesn't have to sit next to the crazy females in class, but he recognizes him on sight when they enter the same street. Like the other children, Shikamaru is tiny and all too fragile for Sasuke to ever try to hit, but he has noticed that Shikamaru doesn't really try either, though he doesn't know why. This is the only thing keeping him from turning tail and bluntly running away.
Unfortunately, to get to the shop he needs that is currently having a sale of 50% off on all food products, he needs to pass the boy on the other side of the road.
Sasuke doesn't stop walking, because it's not really that big of a deal, they were living in the same village so eventually he had to run into someone he knew, but he does look away and doesn't pay him any attention.
When they enter into the same shop, he doesn't think anything of it and instead goes out of his way to get as much food as he possibly can, a sale this good far to rare for him to not take advantage of. Shikamaru is still following him around when he leaves the shop with bags full of food and seals all his stuff into the scrolls he was carrying, making it much easier to drag home and, satisfied, he turns around to the boy that seems determined to stalk him and asks, "Are you going to follow me home?"
The boy mumbles something under his breath and Sasuke thinks that it might be troublesome, but doesn't dwell on it. "You're almost at the bottom of the class you know, and Iruka-sensei wants me to find out why."
He gives a short, "It's boring." and turns to walk away.
Unfortunately, Nara doesn't seem to get the hint as all he does is keep following him and although Sasuke thinks he should be annoyed or something, all he gets is a faint nostalgic feeling. He doesn't say anything when the boy follows him all the way to the Uchiha Compound, but stops when they get to the gates and turns back around, having the unsettling feeling that he didn't want the boy to enter.
"From what I've seen, you're not any better off." he says and gives him and annoyed look.
Shikamaru answers, "It's boring." and doesn't say anything else.
Sasuke blinks at having his own words thrown back at him, and gives the boy a considering glance. It's the first time he's having an actual conversation with someone his own age (but it's not his age) since the massacre and he finds that he doesn't know what to say. Being social is exhausting in a way training never is and it saps all of his energy in a way nothing else ever does and this is a different world with different social rules then he's used to. He finds himself missing Genos (he misses him every day) because he would know what to do. He misses Itachi and the pain of losing both is nearly enough to make him snap at the kid, but he has better self-control than that. He has to, or he would've hurt someone he cares for a long time ago.
But still, the world is far too confusing and new and his patience to deal with questions has never been the best, even as Sasuke, so he takes a deep breath and again says, "School is boring. And I don't care for my grades. Grades don't matter in the real world."
Shikamaru gives him a considering look, hums and turns to walk away. Sasuke breathes easier knowing that he's gone and he enters the Uchiha Compound to find it exactly like he left it. Cold and empty.
The memories are confusing, but he thinks that he used to care about school. He used to care about impressing his parents and catching up to his brother at the same time as he thought that no-one ever could, because his brother was obviously the best. But that was before he remembered things that didn't exist, like planes and aliens and heroes and villains and people that couldn't exist. That was before he found that the world that was once in black and white was suddenly a rainbow of colors that switched places all the time.
This world doesn't have heroes and villains, but it has villages and Saitama knows (he doesn't) that this world doesn't have good and bad, only opinions. Even in his world, there were times when the villains weren't villains at all and all they wanted was recognition for skills people refused to see. All things are relative, he knows, and he doesn't think this world is any different.
Sasuke drops the groceries on the table and starts clearing it away. His fingers twitch and he wants to call for Genos to help him, the expectation of seeing him when he turns around still there (he doesn't think he will ever lose it) and he scowls at the air when for a moment he sees a phantom image of Genos standing there. It's all in his head he knows, but that doesn't make it hurt any less.
Nothing ever does.