Well this depends on the role-playing aspect. Like obviously, if I have a char. that's gonna join the DB, it doesn't make sense to kill him. But I did have a character (Igodah Go^Pe) who accidentally murdered someone. Later on, after she got her visit from Lechance, I learned it's possible to kill the guy and I was SO MAD because I didn't want to be stuck carrying that Blade of Woe. Nor did she want to do DB stuff. So instead of doing their quests, she murdered as many DB members as she could 'till they kicked her out! :wink_smile:
My dark elf witch character got a visit from Lucien, too, but she didn't kill him. She merely accepted him as yet another one of her tortured nightmares. Nor has she done (or will do) any DB stuff.