In terms of my head canon I assume part of the problem is that Karlach's soul was probably traded away, not just her body, so that would complicate things, because infernal contracts almost always involve somebody's soul. Though we're never told if a contract was ever formally signed or if the contract was only with Gortash. It's the lack of specific detail that really makes this difficult for me.
For such a serious issue, there's a lack of real discussion about other options in dialogue; your character can occasionally say stuff to the effect of "we'll find another way", but there's never any discussion about what those ways might actually be. Meanwhile every time returning to Avernus is discussed, Karlach shuts the idea down in no uncertain terms (understandably) but when Wyll offers at the end she immediately accepts with no discussion of that. There's never any real discussion about going back purely as a temporary measure until a permanent solution can be found; Dammon says he won't give up looking for a way, and as others have pointed out there's no shortage of possibilities in D&D, but we never get to really explore any of them.
I'm currently running an actual D&D campaign set around Baldur's Gate, and I purposefully set it 40 years into the future so I could handwave events in BG3 I wasn't aware of yet; while my intention is to now establish a bunch of it as canon based on my first playthrough, I'm very likely to change some things too, and Karlach's fate is definitely going to be one of them. Especially since I already established my player character (Filius Hempenbrow) as a retired adventurer in his early 70's, with a wife the players haven't met yet, and the core of the campaign is an unknown entity that seems able to grant impossible wishes but has an agenda of its own…
Last edited by Haravikk; 19/08/23 09:03 AM.