Palm To Palm

All Might went into an orphanage for a charity event and came out with a new lease on life and an adorable-- if not slightly traumatized-- son.

Izuku is a boy with open eyes and a kindness that stretches miles and miles deep. He knows more than any ten year old should, and Toshinori is aware of this. He's been aware of this since the moment he crouched down in front of the boy and let him press their palms together. Now Toshinori is impossibly smitten and determined to heal Izuku the same way he helped heal him, no matter what challenges jump in the way. He'll protect and build him up no matter what. For his son, nothing is ever too much.

Of course, he never claimed to think fatherhood to be easy going in. He just... hadn't thought it would make him want to Detroit Smash some cocky brat named 'Kacchan' through a wall either.

Or: Izuku heals All Might on a whim and gets himself a new, (extremely overprotective) dad in the process.