@Dekuiru your welcome
A little younger
When they were babies rei exchange them(deku and shoto) enji, fuyumi, natsuo and touya knows that because the two of them (rei and enji) fights about it
PS. I found a story similar that's why I wanna let the bnha know that. The story is in the "Archive of our own" the title of the story is "The Unlikely Todoroki"
U can search it if u want. U can also read it..