Louie is Captain Olimar's sidekick. He appears first in Pikmin 2, where he serves as a partner to Olimar in commanding Pikmin until the 10,000 Poko goal is reached. He is responsible for the debt Hocotate Freight suffers; as it was truly he who ate the load of Golden Pikpik Carrots. After Olimar and Louie get the entire 10,000 Pokos worth of treasure, Olimar returns to Hocotate, only to find he forgot Louie. Olimar and the President of Hocotate Freight return to the planet to find him.
Louie wanders around the planet aimlessly and hopelessly for a bit, as seen in the credit roll of the game. Olimar and the President later find him hidden deep in the Dream Den with a Titan Dweevil. They rescue him and send him to the ship's treasure hoard, since the ship used for travel is already full, calling him the King Of Bugs.
It is often of constant debate if Louie was a captive of the Titan Dweevil, or in actuality controlling him. E-mails the player recieves from Louie's grandmother reflect that Louie always loved bugs as a child, so this theory is almost very feasible.