Hearing Sirius apologize was something Remus had initially wanted when everything first went down. He never would have demanded an apology, but he'd hoped for one to come of Sirius' own accord. Now that he was receiving one, it didn't feel so good. It just made him hurt even more. Seeing Sirius so broken -- Sirius, who was the most outspoken, confident, happy-go-lucky bloke Remus had ever met -- just made him all the more upset. But he couldn't make this about himself. He had to help Sirius.
"Shh," he soothed, continuing to stroke his hair with one hand, and securely hold him with the other to help him feel safe. "Just rest now, all right?" He laid his cheek atop the other boy's head. It was killing him to hold him like this, and Remus briefly wondered if it was indeed possible to die from a broken heart. If it was, then he wan't going to last much longer.