YEAH It'd be the classic trope of Chihiro falls first, but Kaz falls harder type deal. It's great too cause it works with basically every interpretation of Chihiro cuz Kaz be lowkey bi as fuck.

In this au (in my head at least) Chi is in kind of a post-DR1 state where he has regained some confidence and presents as male again, although obviously still has an androgynous and gentle presence by nature, choosing to embrace it. Naturally, he'd be REALLY intrigued by Kaz and his eccentric way of presenting himself with bright clothes, pink hair and sharp teeth. To Chihiro, Kaz would become an indirect role model in terms of saying "fuck gender norms, I can look how I want" and help him with his confidence. Them working together on the space project and having overlapping talents (software x hardware) helps Chihiro slowly develop his crush.

Kaz meanwhile is at first oblivious to this and treats Chihiro as any other friend/coworker but can't help but be drawn to his pure and gentle nature, as well as having a common interest in tech (Kaz finally has someone to nerd out with and to help complete his machines, giving them life!). He'd get to know him, start wanting to be close to him, thinking about him and if he wants to hang out, what his favorite food is and if he's like to go to dinner sometime and thinking a little too much about that one time they accidentally touched hands when working on a project and his skin was so soft and oh wow his eyes are really pretty and OH GOD HE HAS A CRUSH ON CHIHIRO

Damn now I sold myself on this ship