The Sims 2: Apartment LifeEdit
In Apartment Life, roommates are only available for those who live in apartments. They are treated like pets - selectable, but not controllable, unless the "boolProp controlpets on" cheat is used. Roommates have jobs and go to work, but their salary will not contribute to the family funds. Their only contribution is to reduce the rent price.
A roommate can be found by using the newspaper or computer. Sims can also place an ad over the phone. Occasionally, Sims will receive phone calls from social group townies who want to become a roommate. The number of roommates available by newspaper and computer will decrease if the searching Sim's reputation is worse than Dubious Delinquent. Only social group townies are available as roommates through the newspaper or computer. Sims can ask any townie to become their roommate if their relationships are high enough.
The Sims 3: University LifeEdit
Roommates return in University Life. Roommates are Sims that share the player's family home and expenses, but are not part of controllable members.
Sims can obtain roommates by using their smartphones. Once a residential lot is filled with uncontrolled roommates, a new "Roommates" option appears when interacting with the Sims. Sims can "Mooch", "Ask Roommates to Clean, Fix Broken Objects or Make a Meal", and "Dismiss Roommate". Dismissing a roommate will remove them from the household, and they will be replaced with another one. The roommate service can be disabled in the phone Real Estate option, which will prevent roommates from being replaced with another one. With so many Sims around the lot, it will probably be good idea to either lock the doors or to claim a bed.
If a Sim builds up a strong romantic relationship with a roommate, Sims can eventually propose and get married. When playing in the home world, any roommate the Sims marry will become the member of the household.