SleepyHeadLily
It all started from you standing up to your brothers bully. You and bakugou are rivals always at each other's throats about everything. It's as simple as who gets to eat dinner the quickest. However, that makes you two the closest people you both have. You two are always together, whether it's competing against each other, or just hanging out as friends (Friends in denial). You work really great together as heroes, practically unbeatable when partnered up together, only because vilians cant handle the heat of your competition. Your competitiveness goes so far to the point you both tease each other to see who fumbles first, until one day, you realize your heart beats faster around bakugou, you can't help but think "why that loser?"
I'm not following the order and lore of the anime, I'm mostly going to focus on building the relationship. Enjoy <3