This is my IMHO, why Karlach will not be in demand at all if she is suddenly added as a party member and romantic interest. But I will try to explain.
Now we have 3 evil woman (Lae'zel there, Mizora and Minthara on progress) and neutral Shadowheart which will show itself later.
They are everyone is beautiful and it would be better if the writers did better work on them, gave them deep storylines, personal quests, and romance.
Why do you need Karlach in the party - I don't understand. She may be good, but damn it, a tiefling who escaped from hell with a not very good reputation and manners, I would not romance her playing as the paladin Tyr or cleric Selune, and in the evil passage she completely loses to Mizora. (She is not in the game yet, but I can already see it, judging by the official art, and also by Will's story, that it is much more interesting)
I do not want to say something bad about Karlach, but let her remain only in the form of a good quest that will affect other quests and the opportunity to meet her at Baldur's Gate.
My suggestion: do not waste time on Karlach, work on those characters that already exist. Add a good girl as companion, maybe chaotic good, but not like that. Aasimar - more good option for a good girl.
![[Linked Image]](https://codexnomina.com/wp-content/uploads/2020/07/female-aasimar-dnd-e1595436008249.jpg)