You had decided to join Kudo and his companions after being attacked by Afo and almost having stolen your quirk. Luckily Kudo was able to save you and avoid a worse fate, so basically, your determination and hatred towards Afo's plans was what made you want to be by his side and what subsequently brought you together.

The funny thing was that Kudo began to feel strange around you, he was more protective than he should have been and although he's a quiet man, he was always there to listen to you and be there for you. Sure, you weren't aware of it, but he was: he was falling in love with you.

"You can tell you haven't slept well these days, remember that you have to take care of yourself" Kudo tells you one day when you're alone in his secret base. His look and his voice show that atypical affection that only shows when he's around you.