When you meet the group hunting Karlach, they too have an awful story and a very good reaso behind their mission; they are not, as Karlach suggested, a rabid bunch dead-set on getting her head for "reasons" but a lawful good group of ex-Tyr paladins who lost everything in Elturel, and who agreed to make a pact with Zariel to help the helpless;
Moreover, when you expose them as servants of Zariel, the halfling woman tells their comrades to bar the doors (with the intention of killing you), and Anders stops her saying: "No, we're not murderers". I couldn't bring myself to fulfill Karlach's request after that, so I just healed her (she stands on her feet again) and left.
