Bridget is the main protagonist from An American Tail.
On An American Tail, Bridget appears with brown fur with tan tone around her eyes and on her freckled muzzle. She has red curls in a ponytail with a small white flower on top. She wears a three tone green dress with a purple belt (notably her tail is not shown outside her dress) and wears flats. On An American Tail: Fievel Goes West, she wears a dark blue dress and has a dark blue flower on top of her head.
An American Tail
Bridget is a mouse rights activist of Irish decent. Her parents were killed by cats in 1884, whether she was in Ireland or New York at the time is unknown. But this incident is likely what led to her becoming an activist against the unfair mistreatment mice suffered from at the hands of the cats of New York. She is first seen giving a speech in a back alley, imploring any mouse listening to get together and do something about the cats. It's about then that she met Tony Toponi. She seems to be just as attracted to Tony at first sight as he is to her. She also takes an immediate liking to Fievel, and agrees at once to help him, bringing them both to Tammany Hall. This is fruitless however, because Fievel's family was new to America and Honest John didn't know them yet. It is evident that Bridget, being politically active, knows people in high places. She sits on stage at Gussie Mausheimer's rally and was possibly one of the key figures in the building of the Giant Mouse of Minsk. She lives in a water tower atop a downtown building, and lets Fievel stay with her while he searches for his family, likely acting as his caretaker along with Tony between the scenes.
During the Great Fire caused by Warren T. Rat on the pier where Fievel gets lost, Bridget finds Fievel's hat, and later when she and Tony run into the Mousekewitz family, she shows it to Mama, proving Fievel is alive. She joins the search party for Fievel, and is last seen kissing Tony while falling into a puddle after Fievel is reunited with his family.
An American Tail: Fievel Goes West
She appears alongside Tony in a few cameos in Fievel Goes West, always with a child in her arms. It can be assumed that she and Tony have started a family by then, and moved to Green River. Neither speak in this film. Since this event is retconned, Bridget's future concept remains unclear.
Reasons for her absence
Her absence in the direct-to-video sequels became controversial (The Treasure of Manhattan Island in most particular due to Tony's pursue with Cholena) and is largely theorized. For instance, her original voice actress, Cathianne Blore, was in poor health at the time the direct-to-video sequels were produced, battling cancer, and the creators were unable to find a replacement voice for Bridget, causing her role to be dropped from the direct-to-video sequels, as well as having Tony as an unmarried adolescent that motivates his time with his best friend, Fievel Mousekewitz, during those two sequels.
Despite these changes. Bridget and Tony are still the franchise's official main couple and has since been sacredly well-regarded by fans. The concept involving Tony pursuing other female mice is withdrawn from the fourth movie.