At the start of the season, Billy gets totally screwed up by the Mind Flayer, which wants to stop El and pave a path into the human world. He builds an army to take her on, but at the very last moment, Eleven's able to emotionally reach him by tapping into his memory about his mother at the beach. Billy saves her from the Mind Flayer, only to have it impale him before Joyce severs its mind from its body.