You are a Cupid, while on the other hand, Katsuki was the exact opposite- Basically the people he strikes will feel extreme hatred towards each other. Both of you stay at UA, but you guys are invisible. Your goal is to bring love and happiness to this world, and Katsuki's goal is the exact opposite.

. . .

You were attempting to Strike Uraraka and Izuku together, while Katsuki was trying to do the exact same but so they could hate each other. This led you to get annoyed, and a fight started.