My Argonian is a member because he's your Duke Nukem / Terminator / stuff type of a bad ass. He comes without stupid catchphrases though. And there aren't sunglasses in Morrowind.
Immersion? Bah! That guy could use a pair of sunglasses after an assassination.
So, he makes a living by assassinating people. There's kinda much money moving in that business. Nothing personal, nothing special. Just another day at the office. He's going to be the Exalted Master and then waiting the current Mr. Big Shot to retire peacefully when he so wishes. (Never! I like Eno Hlaalu too much to let him go. :′()
Sometimes this Argonian murders some guys if they just annoy him too much. Call them gray writs if you will. This man is a bounty hunter. That's just what he does best. I don't know if he's generally a bad guy though. He might steal. Okay, he might murder occasionally. Just your average bounty hunter thing going on though. He's not some aggressive madman, though. A cunning Argonian, not a savage Orc.