An eccentric chef with a French accent, he is obsessed with cooking and clearly takes great pleasure in it, dancing and spinning around his kitchen while singing about the things he's cooking while doing things that make the hidden Sebastian want to throw up--but that's probably just because all the dishes involve fish or other sea creatures. He's got a hair-trigger temper, which flares up and causes him to get in trouble with Carlotta when he destroys the kitchen while chasing Sebastian. If the sequel is any evidence, his relationships with Sebastian and Carlotta have not improved, though he's still in the royal family's employ anyway and is seen preparing a massive cake for Melody's birthday.
Chef Louis only appears in two scenes of the film. He first appears in a kitchen of Prince Eric's Castle, singing Les Poissons and cooking fish dinners for Ariel, Prince Eric and Grimsby. Sebastian the crab comes into the kitchen to hide from the maids, but Louis eventually spots him after removing a leaf from the counter and attempts to cook him. Assuming the crab was dead, he puts Sebastian into a sauce, dabs him with flour, stuffs his mouth with bread, and tosses him into a pot of boiling water. As Sebastian attempts to escape, Louis attacks him and chases him around the kitchen, causing a big mess in the process (Sebastian pinches him on the nose, Louis gets his hand burned on a hot stove, and a large pot falls on his foot). Eric's maid Carlotta, who has heard loud, crashing sounds coming from the kitchen, goes over to investigate to find Louis trashing the kitchen. Carlotta angrily demands to know what Louis is doing, to which he sheepishly expresses his sorriness, smiling nervously. Carlotta then takes the platter of fish, and leaves the kitchen.
He reappears at the film's finale, onboard the wedding ship for Prince Eric and Princess Ariel, where he spots Sebastian on top of the wedding cake, and resumes pursuing the crab. But Sebastian uses his claws to cut a rope to stop Louis, who gets whacked in the face by a wood beam, causing all but two of his teeth to break and fall out of his mouth. Louis then faints as Sebastian jumps off the ship and celebrate his victory over the relentless chef.
Louis appears in three scenes in the direct-to-video sequel. His first scene shows him preparing Melody's birthday cake. He then chases Sebastian around the dance hall after he lands in Melody's cake during her party. In the end of the film, he is grabbed by Carlotta and they both jump into the sea.
Occasionally, his rivalry with Sebastian comes up for comedy, but his appearance will always be very brief and usually not really relative to the plot. In The Little Mermaid series, Chef Louis steps on a whisk which lands in the water, which Ariel finds and calls it a "Whirly twirly".
In Marsupilami, Chef Louis appears in multiple episodes: in one he is an angry hotel guest who discovers that the hotel manager is none other than Sebastian.
While Chef Louis doesn't actually appear in the Aladdin TV series, Genie transforms into him in many episodes. Genie first transforms into him in "Raiders of the Lost Shark", where he tries to prepare "turkey surprise" for Aladdin (using live ingredients, including Iago for the "turkey") but is politely turned down. Like Chef Louis, Genie tries to cook a living animal, being Iago while Chef Louis tries to cook Sebastian.
He appears in the episode "Goofy's Menu Magic", where he does a short onstage act in which he tries to cook Sebastian again. He is later asked by Mickey Mouse to take over in the kitchen since their cook, Gus Goose, has eaten all the food for that night, but he tells Mickey "This cook is booked!"