Can't decide if Fatui!Luc would be so gentle with his body worship that it makes Kaeya cry while he's effectively tied to the bed, gagged and eyepatch thrown out as Diluc pushes himself inch by inch into his well-prepared pussy or he thrashes him around while bending Kaeya into multiple positions, fucking him hard and fast and reinserting himself once Kaeya begs for him to stop, using him as a little fucktoy and going only a little gentle when he's sobbing in his arms but completely giving in, opening his legs as he no longer asks him to be gentle with him. Hushes him and kisses his face as he pounds into him, satisfied that only Diluc would make him cry, satisfied that only Diluc would break him. I like both. I know both would break Kaeya mentally. He would be stuck knowing only the way Diluc treats him. He'd be forced to acknowledge that Diluc is his whole world after capture.