Heck, if we had a mini quest in Avernus related to Karlach - house of hope could have been a good start but nooo, once again related to Lae'zel's questline! We could find ways to fight for her heart, meeting Zariel, her giving her some sort of ultimatum or something (some kind of a trade off much like with Shadowheart).
But no, we don't even try. The game literally doesn't allow us to try.
Because Zariel would've curbstomped our party without much trouble. As for House of Hope, Karlach wouldn't deal with the devil and wouldn't want us to do that. And we tried with Dammon but failed, Gondians couldn't help us, Steel Watch couldn't do it as couldn't Gortash (if he could, he'd try to bail himself out). I know with all the cheesy options that are possible in dnd we could try more, but then we should ask why we couldn't do the same for all other companions. Or ourselves, why can't we make a deal with some demon or Mystra to get the tadpole out?
