Headcanon that Shouto actually doesn’t feel comfortable with being called “Todoroki-kun” – or by his family’s name at all.
Remember, he chose his first name, Shouto, as a hero name. That’s most likely partly because he is not really the most imaginative person and couldn’t come up with a cool name just like that. But nonetheless, he instantly chose his first name over his last name, even though one could think that he would feel uncomfortable when everyone calls him so intimately.
But let’s think about this:
“Todoroki” is his father’s name. Whenever Endeavor doesn’t get called by his hero name, he will probably be called Todoroki. It’s a constant reminder of the kind of man Shouto doesn’t want to be at all. It’s like a brand, a mark of ownership – a reminder to Shouto that Endeavor sees him as his “masterpiece”.
No, Shouto doesn’t really like to be called that. But he doesn’t say anything – it’s only logical that his teachers and classmates would call him that. It’s the polite, the normal thing to do.
But still, he feels almost too grateful when Mina starts calling him “Todo-chan”, or Kirishima just goes with a “Buddy” or “dude” when addressing him. He kind of likes it, feeling freer and better when being called in this personal way.
Sometimes, Shouto hears how Izuku gets called “Deku” by his friends (and Bakugou – does he count as a friend?) or simply “Izuku” by All Might-sensei (their teacher tries not to say that, staying with the more formal “Midoriya”, they all know that, but he slips up often). And whenever he hears that, he kind of wishes that he could also get a nickname. Or if the others could just call him by his first name.
He would really, really like that.
So one days, when he’s together with his class and teachers one lazy afternoon at the dorms, he decides that he has to make the first step towards that. How should his friends know what he wishes for if he doesn’t tell them?
He gathers his courage, hoping that this won’t come over as weird – he is still not sure how one should behave when interacting with people – and says, as casually as possible, “You know… it would be alright with me if you all would just call me Shouto.”
There is a pause as the others stop in what they are doing, be it conversation or games or testing out new hairstyles – faintly, Shouto decides that he should ask later how Bakugou ended up braiding Momo’s hair. Some of his classmates are looking over at him, others are exchanging looks, and he gets more nervous by the second.
Then, everybody turns back towards their activities, humming and nodding as if all of them had decided on something.
Shouto blinks, slowly, unsure what his friends have decided on now.
That is until Mina says, thoughtfully, “Well, “Shou-chan” also sounds kinda cute, right?”
“I completely agree on that,” All Might nods, still skimming through the newspapers.
Aizawa snorts at the both of them. “Again with the nicknames.”
“But, Sensei! Nicknames are cute! I have one for everyone!”
“I dread to ask what my nickname is,” Momo mutters from where she is inspecting her very well-done braids.
“The nicknames aren’t bad at all,” Kirishima throws in, jerking a thump over his shoulder at Bakugou, “Mina tried to call Bakugou…”
“Don’t you dare to tell them that, Hair for Brain!”
“… Baku-chan. It’s quite neat, but he didn’t like it.”
“Well, duh. It was too cute for him, he was probably embarrassed.”
“Say that again, Tape-guy!”
“Young Bakugou, please…”
Izuku chuckles and shakes his head at his friends’ antics.
And Shouto… slowly smiles, even though he is still a bit confused.
Perhaps he should have expected this easy acceptance.
His friends may be a bit weird sometimes, but when push came to shove, they would all be there for each other.
( @saisai-chan, I just had to include your hairstylist-Bakugou, I still love it so much! I hope you don’t mind! =) )