Julian Trimble is a character who appeared in Diary of a Wimpy Kid: Old School. He is a student at Westmore Middle School and was one of Greg's cabinmates that stayed at Hardscrabble Farms for a week. According to Greg, Julian has great affection for his mother and is rarely seen without her. In fact, he is so devoted to her that, in second grade, he clutched his mother's arm as she walked out of the drop-off zone and had such a strong grip that the assistant principal had to pry the two of them apart.
Greg also states in his journal that he might've decided to go to Hardscrabble Farms alone, but after seeing Julian momentarily taken aback by his mother dropping him off, he realizes Mrs. Trimble tricked him into it, to the 12-year-old's chagrin.
Julian and his cabinmates later engaged in team-building activities, including a trust fall, a "Bucket Brigade" game, and an obstacle course made of ropes, which failed due to Julian being unable to tie a knot between him and Emilio Mendoza, preventing Timothy Ames from going to the bathroom.
Jordan Lankey, Julian's bunkmate, who found a tick on the back of his neck, to the entire cabin's shock. He was then sent to the nurse's station to see the nurse with his chaperone, Mr. Jefferson, and was found unharmed. In their absense, his cabinmates (except Greg) went nuts in the cabin.
During the mail call, he burst into tears after his mom sent a photo of her and her pet dog along his letter.
The next morning, Julian was witnessed groaning and clutching his stomach in his bed, next to a half-eaten stick of deodorant. As a result, his mother drove to Hardscrabble Farms to take him home. Before they left, Julian was seen gleefully smiling in the car without any signs of pain, implying that his excuse to go home was falsified.
- Diary of a Wimpy Kid: The Long Haul (First appearance, cameo)