But is it really too much to ask for a happy ending? Just as easily, right after being transferred to hell, Zariel could appear, effortlessly kill Tav/Wyll, and force Karlach into further servitude.
To be fair this event is actually surprisingly unlikely, rather, Tav has a soul and souls are very valuable to an Archdevil so they would likely try to contractually bind them above all else instead of just outright killing them.
