Bassists are not terribly smart. The best bassists come to terms with their limitations by playing simple lines and rarely soloing. During the better musical moments, a bassist will pull his strings hard and grunt like an animal. Bass players are built big, with paws for hands, and they are always bent over awkwardly. If you talk to the bassist during a break, you will not be able to tell whether or not he's listening.
Drummers are radical.
Specific personalities vary, but are always extreme. A drummer might be the funniest person in the world, or the most psychotic, or the smelliest. Drummers are uneasy because of the many jokes about them, most of which stem from the fact that they aren't really musicians. Pianists are particularly successful at making drummers feel bad. If you decide to talk to the drummer during a break, always be careful not to sneak up on him.