Billy had a plan.

'King of Hawkins'? He didn't give a single shit about that. The scholarship, graduation, and the moving letters? It was almost too easy to figure. Today, Billy received the acceptance letter from a university in CA, and he was ready to run a mile with his step-sister - Maxine. Away from his father, away from Hawkins, away from you. You understood it almost too well. You were his friend, after all.

Then what is he doing now, at 3 in the morning, knocking at your bedroom window?