I consider Viconia a slut by a single reason - she lures into her bed a man who she does not love, not even likes (!) and allows herself to pour dirt all over him afterwards. I mean Cnahrname here.
There is nothing wrong when a woman or a man has multiple lovers - if they indeed love them.
However, if a person has sex for money they are called a prostitutes - again it is a gender-independent category; if Viconia [replaced "person", for clarity] has sex without love - well... if "sexually promiscuous" is the politically correct term, then let's call her (Viconia) sexually promiscuous. Which does not make her (Viconia's) behaivour any less ugly.
And nobody says that she should be burned because of that.
At least 5 murders is what she has to answer for.
So it's basically the Flaming Fist Officer's word against Viconia's. He also expects the PC to be convinced that she's evil merely because she's a drow, in that last sentence. If the PC lets the Flaming Fist kill her, he/she's no better than Keldorn doing the same thing.
I think they call it Due Process.
Not to say that Viconia isn't evil, it's just that she's not guilty.
Yes, it is, but what makes me pretty sure that he has the proof, is that he is ready to die(!) in order to arrest Viconia - he goes against 6 heavily armed adventurers alone. And he is not some bright-eyed paladin - he is a hired soldier. It only makes sense if Viconia is indeed guilty of something terrible. If he was not sure, he'd just walked away. Plus, she is evil-aligned *shrugs* I think it is more evil to kill the man. Imagine that he was a joinable NPC - for example Minsc, Kivan or Ajantis, chasing Viconia, not _FLAM2, whose death is of no consequence to the player whasoever (btw, need to restore reputation penalty on that one) - now, it stops being such an easy choice, is not it?
Plus, to keep Viconia alive and in the party the player has to kill the two most interesting male NPCs! I mean, killing BOTH *Kivan* and *Valygar* for her?! NO WAY! That's some sadistic expectation!