Jaq is the leader of Mice and proves to be a good one at that. Jaq was shown to be the first of the mice to actually confront Lucifer and the only one brave enough to take him on alone. Like the other mice, Jaq is caring for Cinderella and thinks of her as a mother or big sister. He holds a brotherly bond with Gus, who he is seen with on a regular basis.
In the first film, Cinderella rescues the mice from traps and the cat Lucifer and dresses and feeds them. They perform many favors in return. Jaq seems to be one of the leaders of the mice, planning strategies to avoid the cat, sneak food, and help Cinderella with her ball gown. The other mice gladly follow his lead. Jaq is thin, with scruffy hair, and speaks a fast kind of pidgin English.he is last seen in the film in tiny palace uniforms, eating and waving at the wedding of Cinderella and Prince Charming.
In Cinderella II: Dreams Come True, In Jaq's Story, Jaq, feeling useless, wishes that he were a human; Fairy Godmother grants this wish and Jaq tries to help Cinderella and the others prepare for the fair until he realizes he liked being a mouse better and returns to normal. In Anastasia's Story, they attempt to help their old nemesis Lucifer win the affections of a snobby female cat named Pom Pom (the mice's, and probably Bruno's, new nemesis) in the castle in the hopes the cats will then leave the mice alone.
In Cinderella III: A Twist in Time, Jaq make their opening appearance helping the fairy godmother prepare for the prince and Cinderella's anniversary party. After Lady Tremaine reversed time and made the slipper fit Anastasia's foot, they helped Cinderella search for the prince, (wreaking havoc in the palace kitchen in the process). They discover Lady Tremaine's use of dark magic by witnessing her cast a spell on the prince to forget Cinderella (and think that he danced with Anastasia). In a plan to steal the wand back, they succeed in taking the wand from Lady Tremaine, but she has Cinderella arrested with a banishment sentence before she can lift the spell on the prince. Gus and Jaq manage to convince the prince that Cinderella is the right girl through a catchy showtune, "At the Ball". They later help Cinderella put on her wedding gown, but the three are magically sent away by Lady Tremaine, who assigns Lucifer the cat to drive them in a pumpkin carriage over a cliff. After they narrowly escape their deaths, Cinderella, Jaq, and Gus return to the palace where the mice attack the entrance guards to let Cinderella through to the wedding.