Riley Abel is Ellie's best friend from the military school in the Boston quarantine zone and the co-star of the Left Behind DLC. She appears in the Liberty Gardens flashback chapters Mallrats, Fun and Games and Escape from Liberty Gardens, and Ellie brings her up during the main story.
Riley is restless, bold and quick to defend people weaker than herself, though she has no problem pocketing what she wants. She hates the military's rule over the zone and backs the Fireflies even when Ellie scoffs at them. Under the bravado she is torn between her new cause and Ellie.
In Mallrats Riley sneaks into Ellie's room after six weeks away, scares her by pretending to be infected, and reveals she has joined the Fireflies. She leads Ellie over rooftops and through an abandoned building to Liberty Gardens, their old hangout, toasting the late mall resident Winston with a bottle she finds in his tent and playing a brick-throwing game where the winner asks the loser a question.
Fun and Games is the lighter half of the night: a carousel ride that lasts seconds, a photo booth that will not print, mocking the loudspeaker announcements, and Riley talking Ellie through a pretend round of The Turning at Raja's Arcade. She then admits the Fireflies are sending her to another city. In a department store she produces the water guns Ellie lost, starts a water-gun fight, and plugs Ellie's Walkman into a speaker so they can dance.
When Ellie asks her not to leave, Riley breaks off her Firefly pendant and drops it, and the girls kiss. Music draws runners into the mall, and while escaping across scaffolding both girls are bitten. Riley talks Ellie out of a quick death and into waiting it out together. Riley turns; Ellie does not, which is how her immunity is discovered. Ellie keeps the pendant afterward and only tells Joel about Riley once they reach Jackson.
Ellie Williams
Ellie Williams is the 14-year-old girl Joel is hired to smuggle out of Boston, and your companion for most of The Last of Us Part I. She was bitten weeks earlier and never turned, so the Fireflies believe her immunity could lead to a vaccine. You play as her in the winter chapter and in the Left Behind DLC.
Winston Asher
Sergeant Winston Asher is a FEDRA soldier who once kept a camp and a horse in Boston's Liberty Gardens mall. In Left Behind, Ellie and Riley find his empty camp in Mallrats, and his notes show how he saw the two girls.
Corporal "Dickhead"
Corporal "Dickhead" is the nickname Ellie and Riley give a FEDRA officer at the Boston military boarding school. He is only talked about in Left Behind, as the man who took their water guns away.
Joel Miller
Joel Miller is the man you play for almost all of The Last of Us Part I. A hardened smuggler in the Boston quarantine zone, he takes a job escorting 14-year-old Ellie out of the city, and the drop-off turns into a year-long trip across the country to find the Fireflies.