False antagonist

In fiction a false antagonist is a character introduced so as to make the plot more memorable by fooling the audiances preconceptions by constructing a character readers or the audiance will assume to be a or the antagonist only to reveal latter that they are not. A false antagonist is generally introduced early in the work of fiction and established to be at odds in some fashion with the protagonist or false protagonist only to have thier role deminished or in a plot twist for them to join the protagonist or to have actually been doing good the whole time with the protagonist in ignorance unaware of the character's motives.