Colette is shown to be an assertive and opinionated French woman who likes to act tough, especially in front of Linguini. She claims that the reason she is the only woman in the kitchen is because she is the "toughest cook in the kitchen". When she is forced to train Linguini, she is brutal and harsh in doing so. She becomes envious and disgruntled when Linguini got Skinner's attention, and almost left her job only because she thinks Linguini is being snobbish.
Her cooking skills are only mediocre at best, but due to her assertiveness, she believes that she knows what she is doing. When Linguini (who is controlled by Remy) stops her from altering his dish, she gets angry at him, unaware to the fact that he prevented the dish from tasting bad and probably saved the both of them from being fired. She is a firm believer of Gusteau's motto, "Anyone can cook". This is shown when she defended Linguini from being fired and even believed Linguini when he said Remy can really cook. She later ends up working as Remy's sous chef in Linguini's new bistro, La Ratatouille.
Colette is the only female cook in Chef Skinner's kitchen at Gusteau's. She is a capable cook who is able to enter the masculine world of haute cuisine. She had defended Linguini from being fired as a garbage boy when Skinner caught him "cooking" the soup in which Remy had made. She takes Linguini under her wing and teaches him the skills necessary to survive in the fast-paced kitchen. She was at first unaware of Luigini's admiration for her. Colette felt disgruntled when Skinner took a personal interest into Linguini, which in fact Skinner was trying to force the truth of Linguini's cooking.
The next day, she tells a sleepwalking Linguini (puppeteered by Remy at the time) that she likes him, and storms out after mistaking his lack of reaction for snobbishness. Linguini awakens and struggles to tell her the truth. Colette, who is puzzled and frightened by his actions and raving behavior and slips a hand into her bag for a canister of pepper spray. Remy desperately makes Linguini fall onto Colette to prevent him from talking further and the two kiss. Colette is equally surprised as Linguini but quickly falls in love, dropping the pepper spray. A romantic relationship quickly blossoms after this incident.
When Linguini suddenly inherits the restaurant when Remy successfully steals papers and will that testify that Linguini is Gusteau's secret son, he and Colette run the restaurant.
Food critic Anton Ego arrives with a challenge for the restaurant, and Colette prepares only to discover that Linguini had no ability to cook. When Linguini defends Remy, Colette listens to his claim that the rat is the real cook. Tearfully, she believes that Linguini has lost it, and so leaves him. However, she remembers Gusteau's motto: "Anyone can cook" (a phrase she deeply believes in) and returns to aid Linguini and Remy in the cooking.
Ego is successfully dealt with, and he requests to see the chef. Reluctantly, she allows Remy to be unveiled as the true chef and Ego leaves, reformed. Later, Gusteau's was closed down due to rats in the kitchen, but Colette has found cooking at a new Parisian bistro, along with Linguini and Remy, with Ego as a patron and queues stretching around the block.
- Aside from being the only female chef in Gusteau's Restaurant, Colette is also the only main female character that appears in Ratatouille.
- In Your Friend the Rat, there is a scene where Remy is holding hands with a little girl that looks like her.
- Colette appears on a magazine cover in Inside Out when Riley pretends the floor is lava in her old home.