Mickey decided to try and kill the survivers from the first movie. He then wanted to get caught an explain to the court/country that in fact movies can create psychotics. But he knew if he would of been the first to do this, that the court would let him go saying that he was just an innocent victim that just saw to many scary movies.
Debbie Salt said her motive wasn't as 90's like Micky's was, but it was more original just plain revenge. Debbie's real name is Debbie salt Loomis. After meeting Mickey on a psycho chat room on the internet. She joined and helped him into college so she could ditch him then finally get her revenge at Sidney Prescott for killing her sweet, lovable and psychotic son Billy Loomis.