Worlds Apart is the episode Masked Rider FanFiction. The episode introduces the character, Erica Keller.
Dex, Molly, and Kelly ran into Molly and Kelly's former schoolmate from middle school, Erica Keller. She snubs Kelly and is nice towards Molly. Both Molly and Kelly tell Dex their history with bad-girl Erica. Erica grew up poor, while Kelly grew up with the life Erica didn't have. One day, Molly and Kelly played a joke on their teacher and Erica was blamed for it and kicked out of school. Molly and Kelly hadn't seen her since. They learned that Erica now attends Leawood High's rival school.