Narvin blinked in surprise at the question. He shouldn't be; Kay had expressed interest in his alien anatomy before. Narvin would almost be suspicious, except the things that Kay asked were innocuous enough, not questions about obvious weaknesses to be taken advantage of.

"I've never thought about it. Excellent binocular vision, I suppose. Keen senses. I suppose our talent for mimicry might be as well, useful for drawing out prey. And then there's--"

He stopped himself there. But...he'd trusted Agent K with everything else, and hadn't had that trust betrayed yet. He might as well add this to the list as well. He didn't doubt that if Kay needed to learn about Gallifreyan weaknesses, aliens in this universe would probably inform him anyway.

"We have an extreme intolerance to acetylsalicylic acid."