I agree, his quests feel rushed sometimes and he has a lot less agenda than any of the other origins. While I like his story and premise, he should also decide by himself to break the pact or not, depending on what we talked with him about it. Similar to Gales dilemma for example. The companions for sure act as if he made his own decision.
While Wyll and Karlach have done special dialogues, if you approach the one with the other and in fact talking their problems out on their own, when you just send Wyll to approach Karlach, in other scenes he has a lot less agency.
"We are all stories in the end. Just make it a good one."
