Work Text:
The day started out normally for izuku wake up, get dressed, eat breakfast, go to school, get beat up and abused, school ends, try to out run the bullies while masking the days injuries. But that's not what happened because while Kacchan was blasting his shoulder he heard a voice mutter "why do you let him do this?" confused izuku looked up and asked "did someone just say something?", stopping for a second Kacchan looked at you like you just grew a second head " who the fuck would talk to you quirkless waste of space" he vocied in his usual enraged tone. After he was done roughing izuku up he heard the voice again "you know you never answered my question" now even more frightened izuku asked a question that had been bothering him for a little while "who are you?", what do you think I'm a voice in your head you idiot""so what should I call you?""I dunno your the main personality, I'm just an off shute""then how about I call you tails?""like the twin tailed fox no thanks""no that's not at all what I ment I was thinking like heads and tails that kind of thing""fine but only because that's the best and pretty much the best name you could think of""how did you kn-""im literally in your head". It tuck some time for izuku to get used to his new bodily roommate but after getting one for all from all might tails kinda quieted down and soon stoped talking as one for all got used more often until izuku forgot the little voice in his head entirely.