Currently rewatching Season 4, Episode 21, where Priya finds loop holes in the roommate agreement to benefit Leonard for once, so Sheldon blackmails her into getting Leonard to sign a new agreement that better benefits him.
The one who really takes on the brunt of this is, of course, his long-suffering roommate Leonard. He has to deal with Sheldon's demands daily, because they live together (until the very end of the series, of course), and Sheldon (being Sheldon) makes him sign a massive, intricate, 'Roommate Agreement'.
The Friendship Contraction. Leonard signs out of his roommate agreement, reducing himself and Sheldon to mere acquaintances, while Howard tries to think of a cool astronaut nickname for himself.
The Recombination Hypothesis is the 13th episode of the 5th season of The Big Theory. In this episode Leonard asks Penny out on a spur-of-the-moment romantic dinner for two, as they contemplate renewing their relationship after their breakup.
("S2 Ep10")
Episode Info Synopsis Amy and Sheldon host a Valentine's Day edition of Fun With Flags; Penny and Leonard wrestle with getting older; Howard and Bernadette make a discovery in their hot tub; Raj is torn between Emily and another woman.
A Roommate Agreement is a written contract between roommates that outlines their rights and obligations while living together. This agreement includes house rules, maintenance duties, restricted behaviors, and more. For a Roommate Agreement to be useful, everyone sharing the household must agree to it.
The Staircase Implementation - The Big Theory (Season 3, Episode 22) - Apple TV.
A flashback in the season three episode “The Staircase Implementation” reveals that the two characters met when Leonard applied to be Sheldon's roommate. That moment, we are told, was “seven years ago”, and the episode aired in 2010, meaning that Sheldon and Leonard presumably met in 2003.