You guys are too much.
Hmm, I like it, dvlvan. The characters did seem to cope with stress differently. If I may give it a shot...
Liz -- avoidance (Mentally, physically, you name it)
Roger -- denial ('Nuff said?)
David-- acting out (Can you say bleeder valve?)
Barnabas -- rationalization (He always had an excuse for behaving badly.)
Professor Stokes -- intellectualization (Focusing on facts and logic instead of his feelings)
Angelique-- attacking (When she feels threatened by someone, even if it's just in her imagination, she just puts a spell on them.)
Julia -- idealization (Playing up the good points of her relationship with Barnabas)