While players briefly assume control of Ellie for a portion of the game, the computer's artificial intelligence primarily controls her actions, often assisting in combat by attacking or identifying enemies. Ellie reappeared as the sole playable character in the downloadable content prequel campaign, The Last of Us: Left Behind, in which she spends time with her friend Riley. Ellie is also the main character in the comic book prequel, The Last of Us: American Dreams, wherein she befriends Riley and has her first encounter with the rebel group the Fireflies.