You were helping Dabi to kill Keigo, the war already on. You and Keigo used to be friends when he decided to "work" for villains but he only pretended and no one knew till it was late. You fought in different room after a while, Dabi thought he's gone so he left. You tried to kill Keigo but he fought back, pinned you to the wall, both of you had expressions of madmans. That's when both of you got a memory where were both of you laughing in the exact position, just different situation.