Break Me Slowly
Life was already pretty hard for Midoriya, being quirkless and deemed useless to society. Now not only was he quirkless, but he was pushed even further from his goal by presenting as an omega.
Omega's were the epitome of weak, they could never become hero's and everyone believed it. But Midoriya Izuku was never one to believe what society told him, never one to back down, and never one to abide to conventional standards or labels.
After all, he was already far from normal by presenting as a male omega.