Swamped

"How high can she jump?" you ask.

"High enough to get good start on climb. Nocta is good climber, too. When I found her, she only jump as high as my neck. Now she jump over my head with plenty of space." He laughs. "Which is good. If she were still only up to my neck, she'd need mask too."

Now it makes a little more sense why he hasn't done anything more hostile. He sees your mask and assumes you must be in on the plan. Definitely not an illusion you want to disabuse him of.

Best to establish yourself as a worried subordinate, then. Let him think he's in charge. Showing a little fear would be good, and you have a convenient way of getting on that subject.

"Is she, ah, dangerous?"

"Not more than me."

That seems to be an answer to a different question than the one you asked. You keep it in mind, regardless.

The information that would probably be the most helpful is understanding what he's doing here in the first place. But outright asking that would make him suspicious.

Well. The best way you can think of is to get some information that you're sure about, and make a comment based on that. Then he might reveal more. So what do you know that you can drop into the conversation?