an aspect i dont see a lot of the fandom explore (as far as i know) when talking about reigen adopting teru is teru's feelings about serizawa joining S&S so here's my take :D
its such an interesting addition to the dynamic especially since claw is the reason teru's parents left and why he spent his days since awakening his power in constant fear of them
yes he changed his outlook in life following shigeo example, but i think him working together with the scars to take down claw is waaay different than living day to day with an ex-member, and not just anyone but one of the ultimate five and the bodyguard of THE BOSS
to him now working with reigen everyday! reigen the only adult teru can finally trust. imagin the anxiety he must feel!
he might try to find any mistakes in serizawa's "act" or be very cold and rude toward him
(AND if we add serirei to the mix, i feel teru would just go crazy lol)
but really regardless i think him accepting serizawa can be a final step toward teru finally accepting himself and his past actions and living past his trauma as very ordinary commoner
i only know one fic and its the one that made me obsessed with the idea
i would love if anyone know other fics or posts that talk about this. please let me know if you know or just share your thoughts with me :b