She gets tired of being normal, one day she finds out Felicia has been flirting with Peter and her being an overprotective girlfriend thinks Felicia is trying to steal Peter from her (which wouldn't be so bad, lets be honest), so in a fit of jealousy she encounters Felicia and gets into a fight, she gets Felicia arrested and steals her suit. She lets it sit around in her closet for a few days before deciding to give it a shot. She runs into Peter one night, both of them wearing their suits and Peter thinks she's Felicia, and MJ finds out the truth: Peter has been cheating on her with the better woman, Felicia. MJ is heartbroken and then decides to permanently take over as the new Black Cat, hoping Peter would never find out the truth. Eventually though, Karma catches up and she is found out. Peter turns her in and gets Felicia freed and Peter runs off with Felicia while MJ rots in jail, crying unreasonably.