Jaq is the leader of Cinderella's mouse friends 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 cares for Cinderella and thinks of her as a mother or big sister. He holds a brotherly bond with Gus, whom he is seen with on a regular basis. Jaq is very smart and thinks and moves quickly.
Gus, or Gus-Gus, is Jaq's best friend and is rather dimwitted compared to his best buddy. Other than his friends and family, his number one priority is making sure his belly is always treated right. Despite his small size, he is extremely brave to point of reckless as a running gag shows him putting up his fists if Cinderella is ever threatened, only to be stopped by Jaq. He is the main target of Lucifer, who prefers Gus out of all the mice because of his plump size and slow speed.
In the first film, Cinderella rescues the mice from traps and Lucifer the cat, dresses them and feeds them. They perform many small 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.
Gus appears in the first scene of the film, trapped in a cage where Jaq finds him and brings Cinderella to rescue him. Cinderella names him "Octavius", "Gus" as a shortened form.
Jaq explains the situation to Gus, and Gus catches on and joins the mouse troop. Gus seems to be a bit slow on the uptake, but brave in a pinch, and speaks even more fractured English than Jaq, who calls him "Gus-Gus." Jaq leads Gus to help Cinderella, resulting in them accidentally playing a prank on Anastasia, leading to Cinderella getting more chores, then hearing of the invitation to the ball. After Perla tells them and the other mice to make Cinderella's ball gown, they are sent off to get the trimming, since Perla has sewing experience. They get into a fight with Lucifer in the dressing room while stealing a ribbon from Anastasia, along with Drizella's jade beads. Despite Perla telling them to "leave the sewing to the women", Gus has fun with the scissors. After Cinderella's gown is ripped by her stepsisters and transformed by the Fairy Godmother, Jaq and Gus, along with two other mice, are transformed into horses by the fairy. They pull the Coach carrying Cinderella to the castle so that she can attend the ball. When the spell breaks at midnight, the horses are turned back into mice.
Later, Gus and Jaq are responsible for stealing the key to Cinderella's room from the wicked stepmother, Lady Tremaine, who has locked Cinderella away. There is a scary moment when Jaq gets trapped in Lady Tremaine's pocket as she decides to check the key, and Jaq receives a painful spanking. The cruel stepmother then nearly douses poor Gus with scalding hot tea before the Grand Duke stops her. The two eventually manage to escape Tremaine with the key and make it to Cinderella's doorway, only to be foiled by Lucifer, who imprisons Gus in a cup. Jaq immediately attacks, and the other mice and birds jump into battle, as well, though Lucifer manages to defeat them. Cinderella then commands the birds to retrieve Bruno, who rushes inside the château and scares Lucifer away. Jaq and Gus then hand the key over to Cinderella, who frees herself and successfully fits on the slipper. Afterward, she is taken to the castle and marries the Prince. Jaq and Gus are last seen bidding the newlywed couple farewell, throwing flower petals while dressed in miniature, imperial outfits; symbolizing their newfound status as residents of the king's castle.
In Cinderella II: Dreams Come True, Jaq and Gus are also present, living in the castle along with all the other mice. It is Gus' idea to make the new book of stories to replace the old one.
In Cinderella's story "Aim to Please," Jaq and Gus help Cinderella to prepare for the ball and give her support when she doubts her abilities. In this story, it reveals that Gus shows a great dislike for prunes. They even help Cinderella make a good chocolate dessert.
In Jaq's story "Tall Tail", Jaq, feeling useless, wishes that he were a human; Fairy Godmother grants this wish, turning him into a footman. Using the pseudonym of Hugh, Jaq tries to help Cinderella and the others prepare for the fair. However, Pom-Pom becomes obsessed with catching the new Jaq on what she assumes to be made up of seven mice. He realizes he liked being a mouse better and returns to normal in order to stop a mad elephant from destroying the fair. Cinderella thanks Jaq for being there when she needs him.
In Anastasia's story "An Uncommon Romance", they attempt to help their old nemesis Lucifer win the affections of Pom-Pom in the castle in the hopes that the cats will leave the mice alone instead of eating them. However, Lucifer goes back on his deal when Pom-Pom tricks him into chasing the mice. The chase ends when Pom-Pom gets doused in water and dumps Lucifer out of spite. Jaq and the mice, who are not happy about the double-cross, give Lucifer a good whack on the head, with Jaq promptly telling Lucifer that "The deal is off!"
In Cinderella III: A Twist in Time, Jaq and Gus appear as the only mice in the movie and make their opening appearance helping the Fairy Godmother prepare for Cinderella and the Prince's anniversary party. After Lady Tremaine reverses time and makes the slipper fit Anastasia's foot, they help 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.
Jaq and Gus manage to convince the prince that Cinderella is the right girl through the catchy show tune "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. After Lady Tremaine is defeated, Jaq and Gus are seen celebrating Cinderella and Prince Charming's wedding.
The mice are last seen in Cinderella III during the closing credits in a picture with a very decorated King, one with them stuffed with cheese, Gus in a rather sophisticated uniform, and the final picture in a photo booth style series with Cinderella, the Prince, and the two mice.
Gus and Jaq are the only mice to appear in the film, while all the other mice are absent due to some unknown reasons, presumably due to the budget cuts in animation.
Jaq and Gus make numerous cameo appearances in the animated series House of Mouse.
Jaq and Gus briefly appear in the film Mickey's Magical Christmas: Snowed in at the House of Mouse, in which Cinderella talks about how she is thankful they are always willing to help her and where at the end, they along with the birds are seen presenting Cinderella with a new dress as her Christmas present while singing with Mickey and various Disney characters "The Best Christmas of All". The Cinderella segment is later reused in the episode "House of Turkey".
In "Goofy's Menu Magic", Lucifer briefly envisions them as chicken dinners after not receiving his evening meal.
In "Jiminy Cricket", Jaq and Gus label the inside of Cinderella's glass slipper in case she ever loses it again.
Emoticon versions of Jaq and Gus appeared in the Cinderella entry of the As Told by Emoji short series. During the end credits, they become involved in a brief chase scene with Lucifer.
In the ABC fantasy drama, Gus appears in Storybrooke as an engineer named Billy, who became smitten with Ruby (Red Riding Hood) in the episode "The Price of Gold". In "Child of the Moon", Billy tries to ask Ruby out on a date at Granny's Diner, telling her he was once Cinderella's mouse friend Gus in the Enchanted Forest, and when the curse hit, he became Billy. Unfortunately for Billy, Belle pretends that she and Ruby are having plans later so she will not have to be with Gus. The following day, Ruby, David (Prince Charming), and Granny find that Ruby did in fact turn into a wolf, and seemingly killed Billy. It is later revealed that Spencer (King George) actually killed Billy to frame Ruby, and put David in the position of defending a killer rather than protecting the townspeople.
He appeared again in the episode "The Other Shoe", where flashbacks reveal that Rumplestiltskin transformed him into a human to escort Ella to the ball. He becomes distracted when a waiter walks by with a tray of cheese and Ella allows him to be excused and help himself to some cheese.
Jaq and Gus appear in the 2015 live-action Cinderella movie, though they play a significantly smaller role than they did in the 1950 film. Additionally, Jaq is portrayed as a female, under the name Jacqueline, and is Gus' love interest. They also have two babies called Teddy and Matilda.
In comic stories, Jaq and Gus were shown to have moved into the castle along with Cinderella. Unfortunately, Lucifer followed them and attempted to continue tormenting them, but as a result, by royal decree, cats were banned from within the castle walls.
Afterward, Jaq and Gus went on to star in comics without Cinderella. They made a guest appearance in the Mickey Mouse comic strip storyline "Mousepotamia", where they inform Mickey Mouse that he is the heir to the throne of Mousepotamia, a medieval country ruled with an iron fist by the Iron Mask. Curiously, in this story, Jaq and Gus are depicted as being the same size as Mickey. Jaq and Gus next appeared in Walt Disney's Vacation Parade #2, wandering through the city (presumably Duckburg), where Jaq decides they need to get a job and answer a newspaper ad to be lab mice for a series of lab experiments conducted by Donald Duck.
Eventually, Jaq and Gus found their way to Grandma Duck's farm, having smelled some freshly-made donuts that Gus Goose was eating. Grandma was at first terrified by the two mice but eventually adopted them after they gave her a peace offering in the form of a birthday present.
Jaq and Gus appear in the Cinderella themed world. Here, time has been frozen by mischievous monsters known as the Bogs. Jaq and Gus are the first to notice, but they are overjoyed when they meet the game's heroine who claims she can help. They take her to Cinderella, who guides the heroine on a mission to defeat the creatures and save the kingdom. Jaq and Gus join her side during so.
Jaq is first present when Ventus is trapped in a mouse cage and informs Cinderella to rescue him. After he's released, he teams up with Jaq to collect materials in order to make a dress for Cinderella and let her attend the royal ball. When Ventus steals a pearl from Lucifer, he gets cornered and Jaq saves him by throwing yarn balls. The cat knocks him down from the dresser he is standing on and corners him until Ventus comes to his rescue. After Lucifer's defeat, they are able to make the dress for Cinderella in time and let her dream come true. Jaq and Ventus later sit by the window, observing the Castle of Dreams in front of them, discussing their dreams.
During Aqua's visit, she gets shrunk to a mouse's size by the Fairy Godmother after Lady Tremaine trapped Cinderella in her room, and meets Jaq, who is with the key and making his way to Cinderella. When he gets cornered by Unversed, Aqua defends him, allowing him to get the key to Cinderella and free her before the Grand Duke leaves.
Jaq and Gus are mentioned by Cinderella in Kinect Disneyland Adventures.
In California, the duo's likeness is seen in It's a Small World.
Jaq and Gus were seen in the Main Street Electrical Parade, and can currently be found the Festival of Fantasy Parade at the Magic Kingdom. In the same park, can also be spotted in the Cinderella's Royal Table restaurant.
In Paris, they make a live appearance at the Dream of Fantasy event at Disneyland Paris.
Inside of the Enchanted Storybook Castle, Jaq and Gus are featured on Cinderella's wall display.
Jaq and Gus are featured in Twice Charmed, which echoes the storyline of A Twist in Time, though vaguely, and Jaq and Gus play a fairly different role (part of which involves Cinderella shrinking to their size).
- Jimmy MacDonald, who voiced Jaq and Gus in the original film, was coincidentally also the then-current voice of Mickey Mouse.
- Gus' full name is Octavius, presumably after the Roman Emperor who was later known as Caesar Augustus, hence "Gus". Emperor Octavius was renamed Augustus when he became Caesar. In the French dub, he is named Gustav.
- The theme park character versions of Jaq and Gus are gray, yet in the movies and other appearances, they are brown.
- Jaq's name is often pronounced differently by different characters. Some pronounce it "Jack", while others say it as "Jock". There are about four total pronunciations of his name, yet he responds to all of them.
- In Cinderella II: Dreams Come True, Jaq and Mary appear to be a couple, since Mary kisses Jaq after he saves the day. Jaq, in turn, kisses her back.
- Jaq and Gus' full names are actually Jackson Hopscotch and Octavius "Augustus" Lollygagger.
- The fast-paced, high-pitched, unintelligible language spoken by Jaq in Cinderella was dubbed "Mouse Latin" by Disney story man Winston Hibler. Because Jaq's use of the language was carried over into Kingdom Hearts: Birth by Sleep, subtitles that appear on the screen do not match what he actually says. However, there are some instances where this occurs, such as when he speaks to Ventus in a mouse trap and uses his trademark phrase, "Zugk-Zugk". If the player speaks to him on a return visit to Castle of Dreams in Cinderella's Room, the writing in the text box will be spelled exactly as he would say it, for example, "Ven-Ven" and "Cinderelly" are used.
- Jaq was the first new Disney character featured in promotional pictures and footage of Kingdom Hearts: Birth by Sleep.