Obstacle Character’s Critical Flaw • [Variation] • The item that undermines the Obstacle Character’s unique ability to impact the Main Character • The Obstacle Character’s Critical Flaw undermines his effectiveness against the Main Character in general, but especially in regards to his Unique Ability. The Obstacle Character in any story has a Unique Ability which makes him uniquely qualified to thwart the Main Character. But in his character as well is a Critical Flaw which prevents him from just totally overwhelming the Main Character. This is again a trait which is unique to this particular character.

From the Dramatica Dictionary