D stiffened immediately at the invitation, Adrian's voice calm and low and making it quite clear that he knew both that D was there and that his own hearing was just as gifted. That there was a chortle of amusement from the parasite before it withdrew beneath his skin again hardly helped matters.

He stared at the door for a long moment, almost considering simply turning away and leaving Adrian to his privacy. It was one of the rooms D hadn't attempted to explore; it was Adrian's castle now regardless of its origins and having an interloper, even an invited one, would likely chafe. D had no reason at this point to take in every room in the place either, so once he'd gotten a sense for where Adrian preferred to spend his time, he made certain not to enter those rooms.

Their senses were enough that neither needed to be in the same room to keep an eye on each other anyway, so the distance hadn't felt a barrier in that respect.

But that made it feel no less strange to be invited in now.

The door swung open in slow silence under his hand and while the invitation had been to enter, D remained largely in the doorway, his dark eyes flitting about the room to take it in quickly before settling on Adrian's pale form.

"...what have you learned?"