The issue with both Sarevok and Viconia is that Larian are clearly fans of the previous BG games and do understand the characters. In fact, we have in game evidence that supports this idea.


Jaheira: Shadowheart. You should know - Viconia was not half so heartless as she liked to appear.
Shadowheart: I knew her well enough. You might have travelled with her for a time, but she trained me. What's your point?
Jaheira: Only that I find it hard to believe that she could have raised you, and felt nothing for you.
Shadowheart: Perhaps she took some pride in her work, forming me to Shar's liking. She certainly relished wielding the rod..
Shadowheart: ... but who knows. Perhaps someone else made her that way, as she tried to do to me.

While we can argue about what Jaheira actually means when it comes to Viconia it's pretty clear that the following description of Sarevok matches with what we know of him from the previous games.


Jaheira: Not... mad, no. Take Sarevok, for example. For as much carnage as he caused, there was always a cold calculation to it.
Jaheira: He craved power, and his bloodline was just another path to achieve it. I saw that same bloodline turned to better ends than Bhaal ever intended for it

So I don't get why they had to shove these characters and change them just for the sake it. In my opinion, they should've been used been used to show that you can have a dark past and still somehow overcome it, where Viconia would've shown a Sheart a more neutral path perhaps and Sarevok would've been the ex-Bhaalspawn inspiration for Durge.

But nope.