Jimmy is an in charge kind of person. He is always trying to control his friends and insists he is the leader of the group. He is mean and sarcastic most of the time, his hobbies including making fun of Hannah and scaring his cousins and his friends. He claims not to be afraid of monsters, as he thinks they don't exist, but after Hannah and her friends from the Fright Side prove him wrong, he becomes obsessed with trying to protect himself from being eaten by Bug-a-Boo. There are very few times that he is shown with a soft side, such as at the end of Scary Godmother: The Revenge of Jimmy when he makes a peace offering with Hannah by asking her to break open the pumpkin container with him.
Jimmy has curly blonde hair, fair skin, a uni-brow, and two small ovals for eyes. His Halloween costume is the devil, consisting of a red hoodie with white draw strings and white horns sewn to the hood, red sweatpants with a long pointed tail, and red/white sneakers. When it's not Halloween, he wears a long sleeved orange shirt with black sleeves and a black #1 on the chest, light blue jeans, and black/white sneakers.
In the first movie, Jimmy is upset that he has to take his baby cousin, Hannah Marie, along with him to trick or treat with his friends. He suggests that they get rid of her, and he tells her a scary story about monsters coming to eat all the children on Halloween if someone new doesn't put candy in the basement of the Spook House every year. They start to follow her down, but run back outside and lock her in the abandoned house, laughing at her terrified face. Jimmy insists they wait to hear her scream. However, they wait all night, and Hannah never screams, and they miss trick or treating. Katie scolds Jimmy for wasting their time and scaring his cousin, whom he was supposed to protect. Jimmy, Katie, Daryl, and Bert go into the Spook House to get Hannah and meet Orson. They get scared by the Fright Side monsters, until Hannah "kills" them with her flash light and they run out of the house to safety.