Fidget is, at first, a cowardly, greedy minion in the employ of Professor Ratigan. He is somewhat forgetful, as he left his hat and Ratigan's list (which allows Basil to track him down and find Ratigan's hideout, respectively) when he ran away the first and second time, respectively. Despite this he is also cunning; he tends to use stealth to carry out the tasks given to him by Ratigan. He isn't a very good speaker, as he has difficulty with speaking properly about what happened to Ratigan's list. In the comics, he is shown to be more friendly after deciding to do good as he is the companion of Olivia whenever she investigates.
Fidget is a bat wearing a dark grey cockney gangster's hat, purple striped scarf, a purple sleeveless shirt, black pants, a black grey shoe, and a peg leg. He has red-rimmed yellow eyes and sharp teeth.
In the beginning, he kidnaps Hiram Flaversham in his toy shop, leaving his daughter Olivia Flaversham all by herself. Desperate to find him, she sets out to find Basil of Baker Street, the only detective with the skills to find him. When she informs Basil that it was Fidget who kidnapped her father and that he was a bat with a peg leg, Basil immediately knew Ratigan was behind the kidnapping, and set out with Olivia and Dr. Dawson to find them.
Ratigan charges Fidget with kidnapping Olivia as a means of blackmailing Flaversham with her life, as he is needed to help Ratigan overthrow the Queen of Mousedom on her Diamond Jubilee. Fidget also is charged with stealing tools and uniforms for Ratigan's gang to use when they overthrow the queen, and steals them from a local toy shop. Basil tracks him there, so Fidget disguises himself as a baby in a crib using only a bundle until Olivia, out of curiosity, comes across the crib and finds Fidget. He captures her and manages to escape before Basil can stop him.
Unfortunately, Fidget later discovers that the list of the things he needed to steal is missing, and realizes that Basil will use it as evidence. When Ratigan learns Basil is on their trail, he almost feeds Fidget to his cat Felicia, but spares him when he finds that Fidget can help him to capture Basil. Fidget tracks Basil and Dawson to a local pub and tricks them into following him to Ratigan's Lair, where he dresses up like Olivia in a bottle to lure in the duo. Basil and Dawson are captured, and are left for dead while Ratigan and Fidget head off to overthrow the queen.
Fidget delivers the fake robotic queen built by Flaversham to the queen, and they capture her to be fed to Felicia. Fidget carries out this task, but instead he is nearly eaten once again when Basil, who escaped Ratigan's trap, rescues the queen at last second, but is saved by Toby. Fidget is tied up while Basil stops Ratigan, but quickly escapes his bonds and once again kidnaps Olivia. He and Ratigan escape on a hot air blimp over the Thames River.
During their getaway, the crooks are pursued by Basil, Dawson, and Flaversham on a makeshift balloon, and Fidget, who is pedaling the blimp's propeller, tries to outrun them. Unfortunately, the extra weight is too much for him and he tells Ratigan that they have to lighten the load, meaning throw Olivia off the balloon. Deciding that Fidget outlived his usefulness, Ratigan throws him off instead. Fidget, however, cannot fly because of his bad wing and falls into the Thames River below, but somehow survives. His boss himself would meet this fate shortly afterwards, though Ratigan would indeed meet his end unlike Fidget.
- In Italy Fidget was called Vampirello, literally "Little Vampire".
- Fidget has several disabilities, notably his peg leg and a crippled wing which prevents him from flying. However, in the comic book, he seems to have overcome the latter injury, however, how this was accomplished was unknown.
- According to Basil, Fidget likes to drink a drink called Rodent's Delight.
- Fidget likes to hang upside-down (much like real-life bats do).
- Oddly, Fidget wears his hat at the end of the film despite that he lost it when he was at Basil's house. This could mean he has more than one hat.
- In the movie, he appears to be absent-minded, but in the comics, he appears to be smarter and brotherly to Olivia.
- It's not clear if Fidget was a carny before or after the movie.
- Fidget has a raspy voice.
- Disney thought of making Fidget a scary, yet lovable character to viewers.
- Fidget calls Olivia, "Livy" as of the comic.
- In the German dub, Fidget is known as "Greifer", although it is occasionally misspelled as "Griefer."
- Fidget is noticeably Candy Candido's final role before his death. Since Candido normally has a deep, croaky voice (as with his roles as the Indian Chief, the Goons, and Captain Crocodile), his voice actually had to be digitally sped up in order for Fidget to sound high-pitched.
- His design is similar to the Gremlins from the 1984 Steven Spielberg film Gremlins.