Pat egy régebbi lakója volt a Vault 13-nak, aki aärroyo tagjává vált, és a Vault Dweller hitvese lett. The name is intentionally androgynous as the Vault Dweller could be male or female. Together with him/her, she/he led the tribe and helped to make it thrive. She/he died years before the Vault Dweller wrote his/her memoirs.
Given the information made available in the various Fallout games, from interviews with Interplay, Black Isle and Bethesda Softworks staff, and canon information on this site it is likely that the Vault Dweller was male and Pat was his wife.
She/he is mentioned in the Vault Dweller's memoirs.