In the rough draft, these secondary and minor cardboard characters served you while writing the protagonist's storyline. Now, in the revision, is their time to shine. Antagonists rule the middle and are there to teach the protagonist what she needs to know in order to prevail at the climax at the end. This learning is not easy and is fraught with dangerous and often unkind challenges.
Fill out a Character Profile for each character, defining goals in direct opposition to what the protagonist wants while also mirroring traits the protagonist is oblivious of and needs to confront and overcome over the course of the entire story.
(For more: Plot Whisperer and Blockbuster Plots books for writers and PlotWriMo: Revise Your Novel in a Month video series.)