Wilma wasn't originally bad... she was just infected badly by a sandmonster. Before that she was great friends with Lotta and Toatapio Nuva who was by then named Tapio. However, when Wilma tried to boldly protect her school and friends from the sandmonster, it infected her.
Wilma was Toatapio Nuva's arc nemesis for a long time, until she was thrown into lava in a fierce battle between Toatapio Nuva, his friends and Wilma.
Wilma had a henchman named Dumpa.