The Disease

Hanahaki Disease: a deadly disease caused by one person's love not being returned or not being known to the person they love. When both Izuku and Todoroki develop the disease, they are forced to confess to the person they love: each other.

This is also an omegaverse. I don't know, kinda just wanted to make a story with both the Disease and omegaverse. The sense of smell omegas and alphas are gifted with will also play a major roll in the story.

Izuku: Omega
Shoto: Alpha