" Left Behind ," the seventh episode of The Last of Us, explores Ellie's past in a FEDRA school where her friend Riley, a Firefly, takes her on a night of fun in an abandoned mall. The two girls share joyful moments of friendship and romance before being attacked by an infected. While the episode showcases their tragic loss, it also reveals how Ellie discovered her immunity after both were bitten, leaving her to face a future without her best friend.
