[ There's a lot to unpack, with a question like that. "Tell me more about you". His thoughts drift back to Stiles, again, who would answer a question like that by making jokes, being stupid, highlighting the better parts of Derek's lycanthropy instead of what Derek instinctively wants to say - that he's designed to kill, to hunt, and that he's supposed to be primal and fierce and cruel. That he could be monstrous, like Peter, if given the right stimulus and circumstance.

Derek just - focuses on answering the direct question. What can he tell from a heartbeat. ]

A lot of things. I'll know if you're lying to me. I'll know if you're sick. Scared. Aroused. Anything that gets your heartbeat up.

[ It feels, again, like he's showing Tate the cards he could play, which, again, makes him feel wired off and defensive and worried about what this could mean for him in the future - but he's really, really hoping Tate's a good guy, and he's not mentioning the chemosignals, he's not mentioning all the other signs he can see in a person. Derek takes another long, low breath. ]

I thought... you would panic, once I started telling you about what I am. I wanted to know when it started, so I could stop, and maybe prevent some of that.

[ But it never started. Unless the drugs were slowing him down, Tate wasn't scared. ]