"Nyarlathotep," he's quick to repeat, along with — "The King in Yellow. Quite the opposite of lovely chaps." It's to settle the names on his tongue but they're also new curiosities to him, names he doesn't know, creatures he's not familiar with. He's made it his business to know as much as he can about so many worlds and planes of existence, but there's much still left to uncover, to learn. That's been made abundantly clear since his arrival here, especially, along with continuing to learn from those who arrive here from places and timelines he's never known or yet journeyed to himself.

While Arthur removes his clothing, the Doctor alternates between looking and not; his mind is always so busy and frantic as it is, but now his thoughts leap so much further ahead, taking in what he shares, putting it up against the things he knows to be true about the universe.

"It sounds strange to say as the Darkwalker's nearly as terrible as they come, but if this Kayne is capable of that, well, so far we have small mercies here," he notes. "I've encountered entities before that could control the minds of others with ease. Get into their heads, turn them against everyone, into puppets." He won't say it out loud, but the one that most immediately occurs to him was one such entity that invaded his own mind years ago.

But he's glanced at Arthur a moment or two, curious about what he's been through and the stories his body tells. More than that, the stories that live beneath. In his mind. Going through that tends to leave other scars, ones less easy to see.

"I have more questions about your time, what you've been through — questions are my specialty. But," he gives a nod in his general direction. "Are you in pain presently? I can help with that if you are."