Just remember, being nice or friendly doesn't mean good, being rude or obnoxious doesn't mean evil.
I'm sure a vampire-spawn can be especially charming and friendly, using it as a front to get his meal ready. Or a cleric of Shar, the goddess of darkness, secrets, revenge and hidden plots, can be very helpful and friendly while giving nothing about herself away and use you to her advantage.
I think Gale and Wyl are neutral, Shadowheart and Lae'zel are evil, and I'm not sure what to make of Astarion since he's got his own mind and will back for the first time in what is likely centuries.
