The Omegas Who Changed Aizawa's World
Katsuki, Izuku, and Shouto, were all abaddoned in an Omega shelter, each for not being good, acceptable omegas. But when all three of them are brought into the Aizawa household, the relationship isn't what they expected. Instead of mating with them, Alpha and Pro Hero Aizawa Shouta is decided on giving the three a decent life, confusing the three sexually frustrasted omegas, who are still struggling between their emotional trauma and their omega needs to be with their Alpha, and with each other.
OR
The poly a/b/o fic with Aizawa/Shouto/Izuku/Katsuki, with no teacher/student relations, but a lot of hurt/comfort, cuddling, degeneracy and therapy.
Read the tags.