One thing I feel I have to clear up for this fic beforehand (aka we have no idea if this is canon for the time being but let's roll with it): Nana's son is abusive and Shigaraki kills his father in self-defense when there's no one to step in.

The question had been haunting him for days, and yet… he just couldn't bring himself to face his father with it. The old man looked too exhausted for a discussion that could get pretty heavy. At least, he had a feeling it would end that way- he himself didn't quite understand what the old report file meant, anyway. It was… creepy, yes. But there was no need to bug others with this.

Regardless, the mug shot kept haunting him, robbing him of sleep, and it was showing- and all it did was make him look more like that image on the first sheet, tainted yellow with age. It made concentrating on studies quite hard, too. He kept getting distracted from his last couple of days' worth of homework he had left for his senior year by musing over all the possibilities one could think of; but no matter how or how many times they played out, one fact remained that made everything redundant.

That person died 14 years ago, when he was 4. He should just shake it off as some weird, unlikely coincidence.

And still, here he was staring into the mirror at this unholy hour, looking at the same face, with the same eyes, at the same scars, same mole, same everything that the man who passed away at the age of 21 had. There's also the stray thought, that maybe, just maybe… he'll die just as young. So unnerving.

The creaking of the bathroom door drags him back to the present.

"Ah… sorry, Izuku, did I wake you?"

"Oh, " the man starts with a yawn, giving an awkward half-wave with a glass in his hand, "don't mind me, just grabbing some water. What about you, though?" he nods towards him, leaning on the washing machine. "Those bags are Gucci, and have been there for a while. Cannot be the weather, that hellish heat wave stopped being a thing a few days ago- and don't think I did not catch you creeping from corners lately." he adds while reaching out for the tap, pouring a cold drink; "So tell me… what's troubling you, Tenko?"

Of course he couldn't hide it for long… especially with the very visible symptoms at hand. Well then… if the opportunity offers itself on a silver platter, you take it.

"I just…" How to go about this, though? He shouldn't have snooped around at all. On the other hand, the other would know if something's sketchy about the story, so it's best to jump the gun. "I think I might have been a little nosy when we visited the police station, and… I feel I saw something I shouldn't have."

Izuku sips on his water, arching an eyebrow while trying to figure out what the youngster wants to say. What could it be, to lose sleep over… and turn his smart boy into a sleepwalker who would keep knocking stuff over or forget about the food in the microwave, like earlier today? At the station, huh… they didn't spend a lot of time there. 20 minutes, maybe…? He met up with Tsukauchi to wish him a belated happy birthday on the way home, and that's what it was. He couldn't remember anything unusual, maybe apart from the mess due to the renovation of the building, specifically the storage room at the time- those files had to be put somewhere. Which is to say, they were all over the place. Maybe there were some gross cases lying about, or…

The realization hits him like a ton of bricks to the face. He puts the glass down on the washing machine. With a grimace on his face and an almost fearful look, he poses a careful question:

"Is there a chance… that you looked into a blue binder… with yellow marking? Right under the lamp on Tsukauchi's desk?"

While he does not remember the yellow detail, the file was definitely in a blue binder… and exactly where described. Tenko gives a small nod that earns a pained expression and an unvoiced "oh, fuck".

Damn right he was at assuming that he shouldn't have seen that. He feels guilt and growing fear numbing his lungs- the last time he felt so terrible was when half a wall ended up being disintegrated in grade school after a kid shoved him inside and closed the locker behind him… and he panicked when there was no answer to his calls for help. Never been fond of tight spaces, but after that, he was certain in having claustrophobia. This was even worse, though… it felt like being the protagonist of some real life creepypasta. And on top of that, he just upset the last person he would ever want to bother in any way or form.

"I'm sorry, Izuku…" he starts, but a gentle hand on his upper arm silences him.

"No… no, I'm the one who should feel sorry about this. I should have paid more attention once I saw that thing lying around." the other says with a sigh, turning towards him to raise both hands to Tenko's face, stroking his hair and cheeks so carefully as if they were made of the thinnest ice. The boy cannot help but notice that he's passed the man's eye level somewhere down the line; it feels weird, growing up. More importantly, though… he looks so sad. "No wonder you've been such a mess lately. It's always on your mind, isn't it…"

He closes his eyes. The silence equals a yes; he's so tired of being a nervous wreck. The soothing light touches are helping, though.

A thoughtful expression rests on Izuku's face. He definitely did not plan for this ever happening. Poor kid must be so confused… even scared. While he, too, got reminded of that nightmare, he cannot even fathom what scenarios had been playing in the clueless boy's head for almost two weeks by now.

"If you want to…" he says as he puts his hands on Tenko's shoulders, gaining the other's attention again, "I can tell you what exactly is going on. Even if it's… rather complicated, I must say."

A curious glint appears in Tenko's eyes; yes… yes, it would be nice to know. Knowing anything for sure about this is much better than the confusing obscurity.

"Could you, please?"

Izuku takes a deep breath, contemplating on where exactly to start for the expectant boy sitting across him, huddled up on the sofa.

"… do you remember… anything from the day we met?" he asks finally. Tenko is not sure how the question is relevant, but figures that it's better not to overthink it- things are weird as they are, why not roll with it.

"Nothing much in general, from those times… only flashes of my room, the kitchen… and the smell of something sour mixing with alcohol." A shiver ran down his spine as he was thinking about the details, and the memories they were attached to. Thank God he did not remember a lot. "But, that day, I remember rather well. I was just hurt by… uh…" a hand unwillingly wanders to his scars; he wasn't comfortable calling that person his father; but, since Izuku would understand regardless, he decided to skip that part: "… and then you came, just like I imagined a hero would, one day," there was no way he could have suppressed that sheepish smile at something so cheesy, was it? It happened to be infectious, too. "… he was very angry, but you took me away. Then, I guess I dozed off, and the next thing I know is that it's almost dark. I also remember seeing Miss Ochako, Shouto… uncle Tenya, I think, and your teacher, All Might. Oh, and… that someone was shouting and scared me shitless later. I don't remember the face, but… I've always just assumed that it was Katsuki?"

"Your deduction is on point," Izuku half-laughed, but fell back into the careful pondering mood again, thinking about how he was going to phrase what he had to say. Because it sure as hell wasn't going to be an easy task.

"Anyway, after we left Mister Shimura fuming and you fell, indeed, asleep… I visited someone. The same person who allowed me to be there for you in the first place. He… wasn't thrilled that I had you with me. Because he knew by experience that I was already screwing way too much with how things were supposed to go down. Quoting him, 'You will not be doing any favors to anyone, son.' But, in the end, he agreed to my insane request."

Tenko was all ears. No idea how this is going to add up later, but Izuku never talked about the day his life had changed. This is all going to be new, and judging by mystery man right at the very beginning, also very interesting.

"You see, this guy, a mere civilian that I met where you saw my friends that evening… and who passed away a few years back, unfortunately… had an amazing quirk: he could send people through time. And 14 years ago, I took the opportunity… to go back 17 years to… well, long story short, to get you."

Blink. Another blink. And then, an expression of both amazement and disbelief.

"You… I mean, we…!?" while he could not form coherent sentences for the time being, Izuku nods and answers the obvious question that does not need to be answered anyway.

"Indeed. We time travelled." he says as a matter-of fact, fondly looking at Tenko's ever-so-slightly changing baffled- fascinated face, bless the nerdy sci-fi fan in him. "This also means that you are technically old as balls, if you think about it."

The boy is taken aback by the notion. A second later, though, he starts counting, because, if Izuku is telling the truth -and hell if he would ever doubt him-, then 18 plus 17 equals 35, and if he took 14… that was 21. 21, like… him.

"Then, the person I saw on that photo…" he mumbled, unsure of what to think of this new revelation, and what to make of it.

"Shigaraki Tomura." Izuku states staring blankly into the fabric of the couch, an unusual dark expression on his face. Tenko has a feeling that he will remember the unseen shadow of that moment for a long time to come, along with the name that escaped him earlier.

"That's the alias he used as a villain, at least. What happened was that… by taking wee little you, from way back there… fucked rather badly with time-space, I guess, and… there was, technically speaking, two Tenkos. Or rather you, and someone who was already dead, instead of… entering a new reality where you did not exist for seventeen years. And which I was not familiar with... Ah. About… the timeline detail, or whatever you wanna call it…" Izuku paused, looking into his eyes for a moment, "I'd rather not tell how I know about that, alright?"

Tenko nods. There are things better left unknown, and from what he heard this far, he wouldn't even need more information to get a hold of the chaos in his head and heart. Izuku, however, seems to have things left to say.

"He was very much unlike you, actually- always full of anger, and hate... Which is no wonder, as life… was not kind to him. At all. He looked so… lost when confused or stuck, though. Like a three-year-old child, looking for their parents in a supermarket… "

Tenko could tell that the other's thoughts were far, far removed from the living room. He could picture the situation, as it happened quite a few times when he was little- him, only as an adult… alone in the streets, instead of standing between aisles; and with no Izuku or Inko, nor anyone familiar in sight. It was a feeling he wished no one ever had to experience.

"But even at those times, no one dared to approach him. Because he was quick to grab someone by the neck. And with a quirk like that, which he was more, than willing to use… it just wasn't something remotely sane people risked." he pauses for a moment, digging up some hazy details from ages past before his eyes focus on the dim surroundings again; "You know… every now and then, I think of… how things would have turned out if I took the initiative, if I… took a different approach while I still had the chance, and then, maybe he wouldn't have… done that."

The cause of death was suicide- it was one of the details Tenko remembered. His heart sank- while he wouldn't dare to touch a living thing with the intent to kill, and while he could definitely be snappy, and a loner… the thing he couldn't imagine was how he, under any circumstances, could come to the conclusion that the best thing to do would be to, just… disappear.

He tries to construct an artificial monster in the likes of what might have haunted Tomura all his life; he never had a reason to know true anger… but he has an inkling of hate. He remembers loneliness like a long lost sibling, too, and fears, small and big, never left him, he meets them every day. A single piece of cinder, burning through an empty chest, like hunger… that's what it must feel like. Or at least that's the closest he can get by fusing all these demons together. It must have taken its toll after a while. That poor man… really wasn't much like him, was he? But, even so…

"Please, don't blame yourself," he pleads in a cracking voice.

"Thank you," Izuku responds, forcing a wobbly smile, "… but I can't help it. If… if mom hadn't been there… god, I was terrified when I saw him approach mom. Because he was dangerous, he had always been… and had a literal arsenal of quirks at his disposal at the time, except… he had already lost it at that point, and…" Tenko felt uncomfortable upon hearing Izuku losing control over both words and voice… all while fighting back tears. Seeing him like this… he didn't like it.

"You know how you say all the time that she is just like you imagined your grandma?" he carried on in a pained tone, spilling out the uncomfortable details he kept to himself for god knows how long; "He… just couldn't make the difference anymore. And started… talking to her, as if…" his voice wouldn't cooperate anymore as 'I didn't want to hurt Father' echoed in his head, like many times before; he decided to take a few deep breaths before continuing. "Then he just, kind of, collapsed, and started to cry. It was… the most pitiful sight… mom actually tried to comfort him. And it was only then, when I… felt the need to help, you know? To think his life was something to save… once it was way too late?" He swallowed hard, wiping the tears away. Tenko scoots closer and reaches out to hold onto the arm he's resting on.

Truth was, as a child, he had always been wishing for his grandmother, a true hero, to come one day, and make everything right. This secret, he will take to the grave. Noone can ever know- especially not Izuku.

"Mom is a greater hero that I ever was. Even though it required that one last, big sacrifice soon after…. she saved so many people. Just by existing."

"She's amazing… but so… are you, " Tenko squeaked out, trying his best to remain comprehensible while clinging to the arm as if his life depended on it; "You saved me. When no'ody elz' would. And… 'am alive… an' abby." he hiccupped at last.

Hearing this, Izuku felt like crying for another reason entirely.

"Yes… yes, you are," he whispered as he reached out to pull Tenko into a tight hug, "and I'm glad to have you here."

"I love you, dad." he heard the boy say through tears and sniffles.

How many times he asked the other not to call him like that, Izuku had long lost count of… but this one time, he will gladly let it slide.

"I love you, too, dear. I love you, too…"

Trivia aka fun fact section for the fic bc I'm lazy and unmotivated to write 4 to 5 chapters of this lmao:

Time travel dude wrote past/alternative self a letter to tell what the deal is. How much Izuku uses this opportunity, what he does in case Mr. Deus Ex Machina is dead in a timeline, and whatever happens to him in general is his own responsibility.

When you time travel this way and alter significant things in the past, there will be 2 of you in the future: the one who couldn't stay put and let things go their way, and the one affected by the changes. You can return to your own life by going back to point before you existed at the time you shouldn't have been around as there cannot be multiple time travel copies at a time, and taking another trip to when you came from without intervening.

Izuku fucks around for 8 days altogether, so he's over 1 week older than he should be. Noone knows this.

Deku travels back and forth 3 times, and this scenario is from the third, aka last option.

The first time he's somewhat late while trying to find the scene and little Tenko gets the scars- in the future he enters, he meets a not-Tomura who is very humble, jumpy, in-your-face and clingy in an endearing way, and also a borderline-fanatic of Deku, recognizing him immediately upon sight. If he did not have anything to worry about, he would be smitten. (On a sidenote, I headcanon Shigaraki as a genderfluid, so imagine him in a cute dress… Thank you. Now you may proceed with your reading and/or your life.) Soon it turns out that this version is also quite damaged, though- the adoptive family got terrible after the mother died as Tenko got assaulted later by the stepfather multiple times… so Izuku goes back, trying to fix things again, but not before sending mail to himself from a fake account about this kid who is in trouble, and a note to Tenko that everything will be okay. Just in case this reality is a thing even after he fucks off. The adventure cost him 3 days.

Upon his second attempt, he gets to the Shimura household before Tenko is harmed. The child gets adopted by a different family who are heroes; he's rather interested in developing support items than going for heroics, though. This Tenko is not only happy, but also knows the local Izuku and immediately notices that something is hella fishy about the one he's talking to. He gets to hear the vague story of the time travel deal and thanks Deku for everything; they become friends of a sort. He dies later when they run into unexpected villain business and sacrifices himself to save Izuku's life. Deku spends the remaining days in turmoil; he's unsure what the better option is. No matter how he goes about things, the person he's trying to save will die or be a wreck.

Defeated, he asks for another time ride back, and contemplates leaving things as they are; in the end, though, he cannot leave someone in need behind, and steps in at the last second. The rest can be followed, I assume.