He hates this feeling of desperate need for Remus's presence. Hates that he very nearly shuts down without him in this wretched place, turning for solace to a bottle. Just like mother, he reminds himself bitterly. He remembers a time when Remus wanted and needed him; on those nights when it was too difficult to gather the energy to even get out of bed. Sirius had been there, been Remus's rock when it had gotten too hard to be a monster. He had kept from James and Peter the real reason that Remus would look so worn down on those nights before the full moon rather than after.
Azkaban took a lot from him and the fact that it took this as well was an almost physical pain in his chest whenever Remus acts as though he's gotten his best friend back and then, when no one else is watching, can't even look Sirius in the face. So Sirius sits once again, alone in Grimmauld Place, his only company his mother. She's silent and he's not in the mood to fight with her.
He sighs and his head thuds heavily against the wall, his eyes falling closed. Cold, wet fingers on his forehead and he jumps slightly, his eyes snapping open at the shock. Remus is crouched beside him, looking concerned. Sirius doesn't bother saying anything, just closes his eyes and allows Remus to help him to his feet and bring him to the kitchen. A cup of coffee is shoved his way and he sips it slowly, knowing full well that Remus is watching him from the stove.
He wonders briefly what Remus would do if he kissed him, but he decides against it and allows Remus to help him upstairs to his room. Remus helps him into bed and doesn't even realize it, but he's clutching Remus's arm, keeping him there and Remus isn't pulling away from him like he had before. Instead, he sits down on the edge of the mattress and waits for Sirius to fall asleep.
The next morning, Sirius wakes to find Remus curled up on top of the comforter, very nearly falling off the bed. He rolls over carefully and pulls Remus further onto the bed. Remus wakes up, but he doesn't protest Sirius's hand on his hip. Sirius decides that later, when they've both woken up again, he'll ask Remus to stay.