He's trying to decide if he wants to sleep in the living room or stay in his actual room when Balthazar knocked. It's safer to be in the living room because of his proximity to the downstairs and the element of surprise if something happens. It's also more dangerous because of the multiple entrances. His room provides a more direct route he can cover, but it's predictable and Alec doesn't want to be predictable at this point. He wants to provide the element of surprise for those who'd want to hurt him. He's on higher alert since the lights went out.

Alec is hesitant to even go near the door, but keeping up appearances is important in this crazy place. He pulled open the door to reveal Balthazar and unclenched a little. Plus he's got alcohol and that really is a good way to start out a friendship. "No one's tried to kidnap me again so I guess that would be yes. Wanna come in?" He's already opened the door just a little wider to give him access.