Louie Mattic was a resident of Alderaan and the uncle of Elam Mattic. By 3956 BBY, Elam had relocated to Taris.
As an Alderaanian, Louie Mattic understood the intensity of swoop gang related violence in the Lower City of Taris. He considered that world to be more dangerous than his own homeworld.
After gifting his nephew or niece, Elam, with a blaster pistol, he instructed him or her on the fundamentals of its operation. Louie hoped this would afford his relative a degree of self-defense when Elam relocated to Taris. Subsequently, he learned that his nephew's brother had journeyed to Tatooine to work as a miner.
In 3956 BBY, Louie contacted Elam electronically to see how Elam was faring in the Lower City of Taris. He inquired whether Elam's brother had left their shared pet, Hyperdrive, behind to keep Elam company. He also reminded Elam to stay away from the swoop gangs and to continue practicing with the blaster. He knew that Elam kept his valuables in a footlocker protected by a password system, and he believed that no one could crack the lock.
Louie was correct in his assessment that even a skilled slicer like Mission Vao could not break the safe's lock, since it was an older model unfamiliar to those on Taris. However, he failed to realize that his message contained all the answers to the security questions that made up the password. Specifically, the password answers were: Hyperdrive was Elam's pet's name, Elam's blaster training was provided by his uncle, and Elam's planet of origin was Alderaan. When the Republic soldier Revan and his allies arrived at Elam's apartment in the Lower City while Elam was away, they used the message to unlock the crate and take its contents for themselves.
Louie is only referenced in the video game Star Wars: Knights of the Old Republic as the sender of an electronic communication to his relative Elam Mattic, who also remains unseen in the game. Louie's message enables the player, controlling Revan, to plunder a crate located in a Lower City apartment on Taris. This action, despite constituting theft, does not negatively impact the player's moral alignment.