Fidget the Bat

Fidget is a bat voiced by Candy Candio. He serves as Professor Ratigan's right-hand man in The Great Mouse Detective. He later is Olivia's sidekick in the comic story, similar to Dawson being Basil's sidekick. He seems to be similar to Creeper from "The Black Claudron" and Lawrence from "The Princess And The Frog".

Movie
In the beginning of the movie, he kidnaps Olivia's father in their toy shop, leaving Olivia 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 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 was missing, and realized that Basil would use it as evidence. When Ratigan learned Basil was on their trail, he almost fed Fidget to his cat Felicia, but spared him when he found that Fidget could 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 run off to overthrow the queen.

Fidget delivers the fake robotic queen built by Flaversham to the queen, and they arrest 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 escapes his bonds and once again kidnaps Olivia. He and Ratigan escape on a hot air balloon over the Thames River.

During their getaway, the crooks are pursued by Basil, Dawson, and Flaversham on a makeshift balloon, and Fidget tries to outrun them. Unfortunately, the extra weight is too much for him, and tells Ratigan that they have to lighten the load, meaning throw Olivia off the balloon. Deciding that Fidget outlived his usefulness, Ratigan throws him out instead. Fidget, however, cannot fly because of his bad wing and falls into the Thames River below, where he was thought to have died but was later revealed to have survived the fall. How we survived and decided to be good we have yet to know.

If he ever appears in the sequel, we will know why he survived and how he reformed.

Comic Story
But during a comic taking place after the movie, he has not only survived, but also reformed helping out Olivia. When Olivia heard about the Sideshow Sea Beast, she called him and Toby and head out for the carnival. He told Olivia that the beast is the talk of the show and that he used to work at a carnival. Fidget even showed Olivia how some of the tricks are done. Once he showed her the attraction, the monster got angry and held Fidget captive. Olivia saved his skin by carrying a chum bucket, which is the beast's dinner. After the beast threw Fidget, Olivia hoped Fidget remembered that he can fly (how he got to fly again was unknown). Once the beast went back to the ocean, Olivia and Fidget celebrated with caramel apples. He probably reformed because with his boss Ratigan gone, he was pretty much lost and had no where else to go.

Trivia

 * 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.