A Main Character's Unique Ability is the quality that makes the Main Character (MC) uniquely able to resolve the inequities in the Overall (Objective) Story. This means that the MC is key to reaching the goal and/or resolving the Overall Story problem, even if the MC is not the prime mover (protagonist) in the Overall Story throughline. This Unique Ability can manifest itself in obvious ways (e.g. a MC's knowledge of some essential TRUTH that is necessary to achieving the story goal), or non-obvious ways (e.g. the CHOICE of a MC for a key bank position allows the successful completion of a money laundering sting operation, yet is only clear in retrospect). What's important is the fact that the MC's Unique Ability helps to bind the Main Character and Overall Story throughlines together in the story.