‘The Last of Us’ Season 2: Who is Eugene, the Mysterious Man Joel Killed?

After over a two-year wait, The Last of Us returned to HBO on Sunday night—though the world surrounding Joel (Pedro Pascal) and Ellie (Bella Ramsey) looks a lot different.

Season 2 picks up five years from where the first season left off, with Joel and Ellie now reunited with Joel’s brother Tommy (Gabriel Luna), his wife Maria (Rutina Wesley), and their son, and heading up a settlement of survivors in Jackson, Wyoming. Here's what to know about what happened, and why the identity of Eugene matters.