When he first started Hogwarts, Remus thought the only person who could understand him was Severus Snape. Remus had yet to make friends, unless he counted Sirius Black loudly demanding to know his name. Snape had only one friend: Lily Evans, who wasn't even in his house. Remus felt there were certain similarities between them, for Snape's robes were also frayed and worn at the edges. They hung too short around his ankles, whereas Remus's hung too long, a sure sign of secondhand robes in both. Snape's greasy hair was long overdue for a haircut, much like Remus's. Snape often looked as tired and worn as Remus felt. He was certain Snape could understand him.
It wasn't until after the first full moon at Hogwarts that Remus understood how different they were. As he limped past the Slytherin table to find his seat at the Gryffindor table, he noticed Snape talking to Lily Evans. She clung to her books, red hair gleaming under the sunlight streaming from the magic ceiling, laughing. Snape laughed with her. Remus's body ached, his fresh scars stinging, and he wanted nothing more than to go back to his dormitory and sleep for the next five days. He felt as if he would never laugh again, and there was the boy most like him at Hogwarts, laughing at something a girl said. Clearly, that one friend made all the difference between them.
Remus hung his head and sat next to Sirius Black, who excitedly blathered about Quidditch through a mouthful of porridge, convinced he would never make any friends.
Not but two months after Remus became the Defense Against the Dark Arts teacher, he found himself shoved into his own mattress as Snape thrust viciously inside of him. Somehow in the middle of an argument over Remus's boggart lesson, a sharp rise of heat between had seen them tumbling into his bed. They both had known of the others' proclivities since their last year at Hogwarts, so it didn't seem so unusual when Snape yanked his robes off, mouth fixed firmly on Remus's neck, teeth sinking into flesh. It still didn't hurt as much as Remus's fresh scars. The transition straight from argument to sex left no illusions about this being anything more than a physical release to both their frustrations.
After Snape came, he pulled away to let Remus finish himself off—the bastard. The irritation over Snape pulling away did not stop Remus from coming hard into his own hand. Taking a few breaths, he sat up, keeping his back to Snape, who he could sense was still on the bed. Remus sighed, feeling empty and cold now that Snape sat apart from him. He wished Snape had at least remained close by, so he could lean back against him, but he knew without asking that Snape would refuse.
"Tell me," Snape asked, his voice dangerously silky, "did you have a good laugh after the Longbottom boy cast his spell on the boggart?"
Remus glanced back at Snape. He sat at the edge of the bed, head half-turned to Remus. His greasy hair hung in front of his face, though his hooked nose still provided a formidable profile against the light from Remus's bedroom window. "Actually, yes. I did," Remus replied, and instantly regretted it.
Snape stood abruptly and slipped his robes back on in sharp, jerky movements. "I suppose that's the difference between you and me. What makes you as despicable as Black. I never laughed during the full moon."
The words cut so deep that Remus shuddered. He said nothing as Snape stormed out, because there was nothing he could say. Snape had sniggered and smirked and sneered, but Remus could not recall seeing him laugh since their first year at Hogwarts. It did not make Snape's japes any less cruel, but it put them in perspective. Snape had begun with more friends than Remus, but in the end he had lost Lily as surely as Remus had lost James, Peter, and even Sirius, the treacherous bastard. They had both lost everyone, but only one of them had lost the ability to laugh.
And that was where, Remus was forced to agree, the true difference lay between them.