S3, E5: Brotherly love brings J.D. when his brother Dan comes back to town while Elliot and Carla begin moonlighting at a veterinary clinic; Tom Cavanagh Guest Stars. -- Dan decides to stay with J.D. for a while, since their mom's new fiancé kicked him out, but after spending some quality time with him at the hospital, Dan isn't sure if he likes the cynical person his little brother has become. Meanwhile, Elliot (Sarah Chalke) tries to deal with her own problems of having a long distance relationship and decides to try moonlighting as a pet examiner with Carla (Judy Reyes) to save up money to go visit her boyfriend as Carla saves up for her wedding.