Lou was the owner of Lou's Tavern, a bar which was usually operated by the bartender Irvine. He was a no-mercy, foul-mouthed kind of a business man that wanted things to go his way with no questions asked or any naysaying.
None of that went to plan when he finally discovered The Narrator, Tyler Durden, and the rest of Fight Club under his bar's basement. He was accompanied by an armed bodyguard, and when he confronted Tyler and wanted everyone to leave Tyler offered Lou to join with them while ignoring Lou's order to leave the basement. Instead, Lou then beat down Tyler after Tyler refused to listen to him and as he was about to leave he was tackled down by Tyler who was fiercely bleeding from his nose and mouth. Covered in Tyler's blood and in total fear, he allowed Fight Club to keep their operations in the basement with his word "on [his] mother's honor."
After that, he became involved with Fight Club and later Project Mayhem with utilization of vans that would help transport nitroglycerin to the assigned buildings that were meant to be bombed.
Fight Club (Film)
Fight Club (Game)