Code Lyoko (2003) : 4x23

Jeremie's cousin, Patrick, comes to visit. Jeremie isn't entirely happy about it, since Patrick is "super cool" compared to him. Discovering another Replika, Jeremie and his friends plan a mission to destroy it, leaving Sissi alone with Patrick. She is able to convince him to let Herve rummage through Jeremie's computer files. Herve discovers Aelita's forged documents and the program running the Skid, his efforts to decipher it inadvertently draining the Skid's power. To make matters worse, XANA possesses both him and Sissi to cause even more damage. Jeremie, meanwhile, deduces that it's his computer back at school causing the damage, and works with Patrick to stop them. Once the attack has passed, Jeremie has Aelita run a return trip to undo the damage caused. The second time around, Jeremie is a bit more appreciative of his cousin, since the two worked well together before. But, unfortunately Patrick goes back to his own school.