It honestly isn't his intent to make Newt nervous, but Sirius finds he's a little pleased to know he has. He's always rather enjoyed making people uncomfortable, after all. Even when it does him little purpose.

He doesn't apologize and doesn't smile, but quickly follows Newt to a Muggle contraption he barely recognizes, watching as Newt slides a glass plate inside it. There's a smear upon it that Sirius can only assume is a sample of Kieren's blood and it takes him a moment to figure out where it is he's to look through. Even after he does, he can't say he understand at all what it is he's looking at and he pulls back a moment later, frowning.

"Is there something I should be seeing?" he asks, feeling stupid in a way that makes him highly uncomfortable. "I know his blood is different from ours. He shouldn't have any to begin with, should he? Isn't that half the mystery?"