Sebastian is Alexandra Cabot's snickering cat, whose black and white fur resembles Alexandra's hair. He enjoys being mean and sometimes appears to go to the enemy's side, but usually only to trick the villain so he can have a chance to help the group escape. He sometimes uses his claws to pick locks. Alexandra sometimes recruits Sebastian to pull dirty tricks on Josie, but even these tricks usually backfire. He protects Josie's relationship with Alan.