Do Not Use Each Other's Things Without Asking. Not using each other's things without asking is one of the more obvious roommate rules. While some people are more casual about sharing, others are not. You have to learn what kind of person your roommate is and then act ingly.
A roommate arrangement is when multiple adults occupy a single unit together. In most cases, the renters are not related, but siblings and cousins can be roommates as well. With a traditional roommate arrangement, all roommates share a single lease.
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.
It dictates what Leonard has to eat each day of the week, what TV shows he is allowed to watch, whether he has a girlfriend stay over, that he has to drive Sheldon everywhere he wishes to go, whenever he wishes. It even dictates when Leonard is allowed to use the bathroom.
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.
Sebastian was Sheldon Cooper's former roommate before Leonard Hofstadter.
The Staircase Implementation - The Big Theory (Season 3, Episode 22) - Apple TV.
Leonard tells Penny about how he and Sheldon became roommates and what happened to the elevator. Leonard tells Penny about how he and Sheldon became roommates and what happened to the elevator.