Bernadette eventually fights to keep her, and Penny declines the rival offer, though Bernadette secretly keeps a napkin with Danny's high-salary offer hidden from Penny. The "Guinea Pig" Day
Leonard realizes his mother, Beverly, performed similar experiments on him throughout his childhood. When he calls her to complain, she reveals that the "experiment" on him never actually ended. [S12E17] The Conference Valuation
Danny offers Penny a job, leading her to realize she doesn't always feel appreciated by Bernadette. Bernadette eventually fights to keep her, and Penny
Sheldon and Amy use the children to test cognitive and motor skills, much to Howard's amusement and Leonard's distress. Bernadette eventually fights to keep her