Halward's blood magic ritual wasn't intended to change Dorian's orientation, it was intended to change his sex. When Dorian escapes and leaves the ritual half-completed, he leaves with a surprise: he can become pregnant, but without the necessary mechanisms in place... it's slowly killing him.

Toshinori's an omega, but he didn't choose it. He focuses on what he did choose - All Might - and endures the rest. A heat accidentally spent with Aizawa results in an embryo, some hard truths about the things he's been ignoring, and new hope.