You and Kaeya have been together for a few years, both of you working as Knights of Favonius. While you're sure there's probably a lot you still don't know about him, he's definitely opened up to you a lot more than anyone else.

When he comes back from a long mission (which Jean did not let you go on with him) battered and bruised, yet with a grin on his face, he gives a pained chuckle. "Hey beautiful."