When Emet-Selch arrives home he'll find Hythlodaeus opens the door in nothing but lacy black lingerie that barely covers anything, and a sheer black floor-length robe that just about manages to cover what the underwear doesn't. He tugs Emet-Selch inside by his belt loop, a devious smirk on his face.

"And now you're all mine until I say otherwise..."

When did he buy these? Who knows- but he was looking for a reason to wear them, and Emet-Selch's picture apparently brought out the need to do so immediately. And perhaps he needs to soothe him a little after his own profile happened to mention that anyone could do what they liked with Hythlodaeus' body- untrue, as Emet-Selch had pointed out.