Boku no red dragon emperor

Izuku Yagi wasn't born with a quirk and was bullied, attacked, harassed and more for the factor which he couldn't control. Ddraig was unhappy having been used as a tool for Isseis pervertedness so when he finally accumulated enough power to leave Issei forever he took the opportunity and fled Isseis body. It was then fate showed a hand and Ddraig fused with Izuku and from there the legend was born a hero beyond the gods for he is the strongest red dragon emperor.