Eh? Karlach is one of the good alligned companions. She's just a war veteran on the run. Hard to be cheery like that. Do you perhaps mean Minthara (drow paladin)?
Could be. I’ve only been catching up a day or two now. Is it possible that Karlach was a non-recruitable quest giver at one point?
She was exactly that, a quest related to some ''paladins of Tyr''. She's a beefy tiefling origin character.
The other character mentioned is a drow paladin companion.