Flak, 50, is pretty gruff, but he's completely reformed from his early days of being a slaver and is an upstanding citizen of Rivet City. He spends his days in the shop with Shrapnel, occasionally taking a break to drink down at the Muddy Rudder. Flak still has a bit of the tough guy in his speech, but he's not as aggressive as Shrapnel. He really tries to tone it down when he's at the shop.
Together with his partner Shrapnel, he runs the Flak 'N Shrapnel's weapons store in the Marketplace. He can sell you ordnance and repair your weapons. Flak and Shrapnel share their store's inventory, so buying or selling from either one of them will update both of their stocks. This means that if Flak is enslaved by the player for Paradise Falls, Flak 'N Shrapnel's in the Marketplace will still be open. They consistently have a larger amount of caps than the other shops in Rivet City. After the Marketplace closes, he goes to The Muddy Rudder for a drink and heads off to his cabin to sleep afterward.
pc If the player chooses to enslave Flak and then releases him from Paradise Falls, he may be found back in Rivet City doing his usual routine. The problem is he is now missing his dialogue options. When interacted with, he will just have a line stating "You saved me from those bastards. I won't forget it." This can be fixed by using the "removefromallfactions" command on Flak.