Gaetan Molière was born to a middle-class working family and was the youngest of four brothers. Both of his parents were teachers. His father, Christof Molière, teaches University courses at the Sorbonne and his mother, Gabrielle Molière, is a retired music teacher.
Gaetan displayed an early interest in subterranean pursuits at the age of seven when he began exploring the vast sewer networks that lie underneath old Paris. By the age of thirteen, Molière had developed a specialized type of goggles and headgear to wear while exploring caves in the surrounding countryside, as the sewers and catacombs held no further challenge or mysteries for him. He entered the Sorbonne at age seventeen but left soon after when given the opportunity to act as a special technical adviser to a local mining company.
Soon thereafter, Molière developed what could be termed his "specialty" of the ability to "taste" and identify various soils. He is sensitive to the light and generally distrustful of those he does not know well. He eats only roots, burrowing animals, and if the rumor is to be believed insects. According to his dossier in the movie, he is 39 years old.
Mole was envisioned to be a comedic character from the start, but the filmmakers and designers had trouble figuring how he should look visually. Many early designs saw a more serious-looking Mole before they saw the way story artist Chris Ure drew the character making him appear more rodent-like. They took that design as the basis for the way Mole would look, adding that he was similar to Peanuts character "Pig-Pen."
Supervising animator Anthony DeRosa had further challenges, due in large part to the character's specialized headgear. Because there were numerous gadgets connected to the headgear, this resulted in more detail and design needed. De Rosa also had trouble looking for a look to the character that made him appear French before finding a profile of Charles de Gaulle and based further facial designs on that.
The voice of Mole was performed by Corey Burton. Burton noted that performing Mole required him to let the character leap out of him by making funny voices. At the same time, he had to throw himself into the same and believe that he was immersed in the film's world as though it were real.
Molière has extensive knowledge of geology and is a pioneer in the new science of tectonics. He serves as an adviser to Mining National du France, Ottoman Mining, Australian Opal Inc., New South Wales Coal, Slate and Granite, Italy, and American Coal and Lumber. He has developed or invented 62 independent mining and excavation vehicles, tools, or related equipment. Molière holds patents on 59 of said inventions.
He has developed acute senses, particularly taste and smell, enabling him to correctly identify any type of mineral or soil without benefit or aid of any scientific apparatus 98.75% of the time.
Mole participates in the expedition that locates the Shepherd's Journal in Iceland. He is later talked into agreeing to locate a giant crystal pictured in the book and sell it on the black market for a hefty price.
Milo James Thatch is warned on numerous occasions by Dr. Joshua Sweet regarding Mole's unusual behavior. This includes Mole's outrage when Milo discovers his bed being used to display the various lands Mole's dirt collection comes from and Dr. Sweet punishing him for his rude welcome and later telling Milo that it would be in his best interest not to know Mole's back-story; Audrey Ramirez once told him that particular story, which she shouldn't have.
When the submarine Ulysses is attacked by a Leviathan, he and Vincenzo Santorini used one of the Sub-Pods to battle the mechanical beast until they were ordered to retreat with the Aqua-Evacs following the destruction of the Ulysses. Mole and Vinny's Sub-Pod is the only one to escape the Leviathan and surface into an air-pocket that leads to Atlantis.
Mole operates The Digger through their journey, used only when running into obstacles too great for or when Vinny runs low on explosives. Throughout the journey, he and Vinny would participate in pulling pranks on the young inexperienced Milo before he is taken in during a rest stop.
When the expedition gets dropped into a cavern as a result of escaping hostile fireflies, Mole is able to determine that they are at the base of a dormant volcano and that it could be reawakened by an extreme explosive force. Upon their discovery of the Atlanteans, Mole becomes enamored with Princess Kidagakash when she displays her ability to speak French, but his attempt at flirtation is met with a punch to the face.
Later, when the group is considering who should "talk" to Kida and someone who has "good people skills," won't scare Kida away, and "speak the language" and Mole eagerly volunteers so to have a chance at her. However, Rourke's hand selects Milo, reducing Mole to tears. Luckily, the Frenchman manages to gorge on an Atlantean lunch shortly afterward.
After the Heart of Atlantis is recovered, Milo makes a plea to the others regarding what their actions will do. Mole is among those who side with Milo and participates in the battle to stop Rourke. He recognizes that the volcano has awakened when the Gyro-Evac crashes and helps bring the Heart of Atlantis is returned to save the city from destruction.
Mole is honored for his bravery in saving Atlantis. Upon returning to the surface, he would outfit his crystal to fit over the center of his bow-tie. However, he displays a sense of discomfort being dressed up and immediately disrobes and buries himself in one of the potted plants Preston Whitmore has in his study.
Mole would join the others in returning to Atlantis briefly in informing Milo and Kida of what is happening on the surface. In their first mission, he is seen in the cargo ship having a meal with Obby eyeing on his cheese. When the Krakken suddenly attacks their ship, Mole drops his cheese, causing him and Obby to try and catch it but was too late as it fell into the water. As Mole mourns for his lost cheese, the Krakken's tentacles appear, causing Mole to tell it that he can have it. After escaping the damaged ship, Mole joins the group in exploring the town, later settling into the inn at the suggestion of Edgar Vulgud, the town's magistrate. Later at night, he is helping the group look for Vulgud, with Mole realizing that his light has disappeared. As the group headed back to what they assume is the village, Mole then notices that the ground is starting to turn into decomposed granite. Before Mole can finish, the group falls over the cliff, with Mole slowing his descent by using his pickaxes. He later rescues Audrey as she falls down the cliff, telling her that she can't live without him. The next day, as the group was looking for a secret entrance, Mole finds it immediately thanks to his knowledge of rocks. As the group discusses how they're gonna apprehend Vulgud, Mole notices that Audrey has been hypnotized. After defeating Vulgud, Mole charges into a group of villagers to make an opening for the team to head outside to their Sub pods. As they are fighting the Krakken, Mole notices his co-pilot, Vinnie, is under the monster's control, causing Mole to whack him over the head with a wrench. Despite some failed attempts, Mole and the team successfully defeat Vulgud and the Krakken.