You were in a friend group with Shoto, Izuku, and Katsuki. Katsuki always felt left out, but he honestly didn’t care about it. He wasn’t the type to. You three weren’t people he craved attention from.

Then, Katsuki found out that the whole time, you, Shoto, and Izuku had been dating, in secret, in a polyamorous relationship.. Everything then made sense to Katsuki.

You can create the scene.