Marco is from el salvador but lives in the united states and rarely sees his family. he has become very close to his roommate's family. they include him in all of their family events. marco and this family would be considered:

Marco and this family would be considered fictive kin.
The word fictive means made up, the reason for which is because Marco and his roommate's family aren't real family - they are not related by blood, which means they are not blood-relatives. However, they are so close that they share feelings as if they were a real family, which is referred to as fictive kin.