It’s destructive, and wrong, Remus knows. He doesn’t even know how much he helps Sirius during the nights, but he can’t seem to leave, can’t deny him when he knows now that Sirius is relying on him, leaning on him. Maybe it’s the guilt from not visiting at St. Mungo’s, maybe it’s Remus’ own loneliness making him reach out to his only real friend, or maybe it’s the fact that he’s been in love with Sirius for longer than he’s known was love was, and has never truly been able to deny Sirius, even when they were children.