The first episode of HBO's The Last Of Us contains a 20-year time skip, during which time almost all civilization falls, and what's left is holed up in quarantine zones, clinging to what's left of society. These quarantine zones are led by FEDRA, the all-powerful and all-oppressive government that is protecting the people from the infected but governing with martial law.
Orphans in these zones are sent to boarding schools to be taken care of until they are old enough to either join FEDRA or be released into the quarantine zone to try and survive. While Ellie was initially in one of these boarding schools, she eventually came to meet and befriend Riley, who is mentioned by Marlene later in the first episode but never seen.
Early Life And Meeting Ellie
Riley was born after the outbreak, and her father became infected and killed her mom, forcing her to kill him out of self-defense. After this, Riley was put into a boarding school, where she came to hate FEDRA even more and dream of escaping the oppression and saving others from it.
Riley eventually met Ellie in this school, and the two became fast friends. Riley was a bit older than Ellie and eventually chose to join FEDRA when she came of age. Riley eventually meets Marlene and sees joining the Fireflies as the better option for her freedom and a chance at taking down FEDRA. At first, Marlene is hesitant to let Riley join and declines to let Ellie join at her younger age. After eventually joining the Fireflies, Riley and Ellie lose contact as Ellie was not old enough to leave the boarding school, and Riley was learning to fight with the Fireflies in another part of the city.
Where Is Riley Now
Shortly before the events of The Last Of Us, Riley shows back up at the boarding school to see Ellie after a while of no contact. The two leave the school and head to a mall to hang out one last time before Riley is deployed to another part of the country and won't be able to see Ellie again. While in the mall, Ellie requests to join the Fireflies so that they can stay together, but Riley informers her Marlene would not allow this.
While in the mall, the two are attacked by infected runners. While initially, it seems they escape, they both reveal they were bitten. After the initial suggestion of them shooting each other to avoid turning, they decide to continue to fight to get to spend just a bit longer together. After being bitten, Riley eventually succumbs to the infection while Ellie continues to live and eventually seeks out Marlene, kicking off the game's events.