I have these characters in older paintings. Not all of them here on artstation, the rest are on my tumblr and deviantart accounts. But it took me so long to detail this one I figured I might upload it here too.
Purely judging by previous pictures one would get the impression that she's a sort of haunting presence. So I wanted to make one where he's consciously and deliberately interacting with her.
Well, that and also I got prompted because I got asked whether they have ever done any strange dance-like arcane rituals (oddly specific question but I liked it).
So the new items here reflect a more occult context. The body chains are more of a playful nod to the idea of arcane binding since clearly they do not actually impede anyone. The chain around her neck would be more substantial if she didn't trust he wouldn't misuse it (it's a callback to an older one where it was on him but she didn't look humanoid in that picture). The talon gauntlets/jewellery have bits of similar shape to the centerpiece of her crown, he's wearing these because it synchronizes their appearance.
Her prismatic wings can refract not just light but other types of waves too, so this was my reasoning behind sometimes having a ripple effect on the look of objects in the environment when she's in a scene.
Ah, and I imagined that she's always had a resemblance to statues like the ones in the background (and can camouflage among them to pretend to be one during the day) but I hadn't drawn and of the multiple places that have them before.