Um, most of the time they don't actually. Snakes - well, most reptiles - are strongly directed by instinct? They don't do a lot of what we would know as thinking, their brains just aren't capable of that or the higher emotions, either.

[As Herbert explains, he gestures a little, his expression bright as he talks about something he knows a bit about. There're few things the Ravenclaw likes more than showing off his knowledge, and if it can impress the gorgeous Thor, so much the better!] They can learn to tolerate being handled by certain people, though, so you should at least be able to hold it!