During the "Strictly Business" quest, capture Susan Lancaster and receive your reward. Afterward, speak with her in the slave quarters part of Paradise Falls. Note: One of the slaver's keys is required to access the slaves quarters; pickpocket one. After entering the slave quarters, speak with Susan and when she asks for help, select the option "You're a slave. Deal with it." Return to Grouse to collect your reward again. Grouse will think that you captured her again. You can repeat this for 250 caps and a slave collar each time.