Rework roles entirely. You start out as a generic adventurer with no special skills, and as you gain levels you choose a path - allowing the progression of your character to follow a branch in a tree structure rather than a single line of progression determined by your role.

The Quest could be tricky to handle in this system, because it has to generate the home level when you first arrive in the branch. After gaining a few levels, your path would be set enough to generate a particular role-like quest, but it’s possible to reach the Quest branch without gaining any levels. One possibility could be if you reach the Quest before choosing enough of your path to specialize, you get a unique “pacifist quest”.