I occasionally get to set in on my old groups weekly Pathfinder game. Recently they've invited me to make a character that can hop in and out of the game. It's an evil party (which is not my normal thing) and the game takes place in the Forgotten Realms. This is a make up of the party (currently 14th level):
Aasimar Monk/Ninja - Cast out from Celestial Court, wants to raze Heaven
(Oversized) Goblin Barbarian/Anti-Paladin - from Golarion, needs to get a key to free Rovagug.
Half-Elf Ranger - Bounty hunter who's recently joined a secret society that seeks to control the political realm of Faerun
Human Wizard - acolyte of the skin (if you're familiar with that 3rd era prestige class), a man that wants to become a fiend
Human Oracle of the Heavens - has a cult following, seeks to be a goddess
While I've not sat down to make him yet, I've decided that I shall play Bastien Douze-Doigts, Dhampyr Cleric. Even though he's only half-vampire, I'm going to play up the vampiric aristocrat aspect. I have the Advanced Race Guide and Blood of the Night and I will be using these to flesh him out. I want him to have fangs and I will be taking the blood drinker feats. I realize I'm talking about "roll" aspects more than "role" but I just wanted to get across some of the basics.
Bastien Douze-Doigts is an aristocrat and socialite. Most see him as a handsome and eccentric noble that throws the best fêtes in the city. However, those in the know claim that he's a vampire who dabbles in demonology. This is only half truth. Bastien is a dhampyr (half-vampire), but he doesn't merely dabble in demonology. He is, in actuality, a cleric of Graz'zt. He even claims to be a son of the demon prince (and his polydactyl nature lends a bit of credence to the claims). As of now Bastien has no major over-arching plots. He is content to practice his hedonistic ways and do his father's bidding.