The werewolf walks among us unhindered. Though the transformed beast is indeed distinguishable from its non-magical counterpart through small yet distinctive characteristics — the length of the snout, the pupils of the eyes, the tufted tail — a werewolf in human form is nearly unidentifiable.

A soft petal of snow fell onto the textbook. Severus brushed it away impatiently, leaving a faint smudge of dampness on the page. In a fit of Christmas spirit, Professor Flitwick had decided to dedicate the last class before the holidays to snow charms, and thus little whorls of precipitation fluttered about the room. Severus had methodically produced the required charm and moved on to worthier pursuits. His research on werewolves had led him on a circuitous plunder of the school library, and though another full moon had come and gone, still he had no proof but the feeling in his gut and the mysterious marks on Remus Lupin's face. All the same, he remained convinced.

But he needed proof.

To the average eye, the monster moves as one of us, hidden behind the safety of a familiar face, crouching behind human skin, waiting to strike, to attack...he lives, always, in the shadows...

Another clump of snow fell onto the page, obscuring the text. It was only at this point that Severus noticed a large shadow looming over his book. He glanced up. Above him hovered an enormous mound of snow. Before he could reach for his wand, before he could even react, it plummeted, falling upon him in an icy, sodden mass. He spluttered, hastily clearing the snow off his book. Laughter erupted behind him.

He turned sharply to see Adam Avery and Evan Rosier sniggering, Avery's wand still pointed lazily at him. A knife of a boy, Avery smirked at Severus's furious expression. Around him, the Slytherin girls were all giggling; Isolde Greengrass, simpering blonde little slut that she was, clung to Avery's arm in hysterics. Isolde had always despised Severus, primarily because she despised Lily Evans, and it was well-known among the Slytherins that Severus was friendly with the Gryffindor Muggle-born. He looked away, cheeks flushing with anger. It was bad enough he had to deal with Gryffindor scum like Black and Potter, but to suffer such indignity at the hands of his own housemates?

The bell rang, and the class dispersed. Severus gathered his now-sopping belongings and shuffled his way out into the hall. Rosier shoved against him, hard, knocking his books to the floor.

"Watch it, mud-licker."

Severus glowered as he collected his books, hateful thoughts spiraling their way through his mind. Students flowed by him like a river around a rock, barely pausing to glance at the boy kneeled on the cold, stone floor. For the first time, he felt pleased it was almost the Christmas holiday. He would stay at school, of course. Severus stayed at school for every holiday. He had no desire to return to Cokeworth, smothered on every side by the squall of mill strikers, the bleating of his drunken father, the wasteland of his mother's gaze. And the majority of students left, anyway, which meant the castle was quiet and empty. That was how he liked it best.

"Sev!"

He looked up, his heart rising at the familiar voice. Lily Evans was hurrying towards him through the crowded hall. He straightened up, books in arm. "Hi," he said. She smiled at him, and his skin tingled, knowing that smile was for him alone.

"Flitwick had you doing snow charms too?" she asked, brushing a bit of snow off his sleeve.

"Yeah," said Severus, trying not to scowl. "I've had my fill of winter cheer, I think."

"Not me," said Lily brightly. "I love winter. Always have. Walk with me?"

He nodded and the two fell into the flow of students headed towards the Great Hall. He was warmed by the familiarity of this act, his long spider strides and her soft, quick steps. He'd missed her. He'd been so absorbed in his obsessive research to prove his theory about Remus Lupin that he'd hardly made time for anything else, but now, with her by his side, he realized what a loss this had been.

Of course, came the bitter thought, Lily hadn't seemed to miss him nearly as much. She'd been spending all of her time with her new boyfriend. Some Ravenclaw named Anson Nott, some Quidditch jock, some pea-brained pretty boy. Severus had watched them together, holding hands in the halls, lurking in the more amorous corners of the library, eating all their meals together at the Ravenclaw table. He didn't deserve her.

Lily, not noticing this darker thread of his thoughts, was chatting amiably about this and that, classes and exams, what she'd gotten her sister for Christmas.

"I wish you didn't have to go," he said before he could stop himself. He was embarrassed to hear his own voice, petulant and childlike.

She gave him a sympathetic look and touched his arm. "I wish you were coming with me. But I understand why you're not. You won't be too lonely, will you?"

"No. You know me. I like it quiet."

They turned down a less crowded corridor and paused by one of the tall, inset windows that looked out over the grounds. Out of pure habit, Severus looked to the sky: The moon, bright as a Christmas bauble, was just peeking out into the settling dusk. He pulled his gaze away. Lily had set her bag on the window ledge and was rifling through it. "I was going to wait for Christmas," she said, "but then I thought, oh, why bother? Anyway, I have a present for you." She withdrew from the bag a slightly lumpy parcel wrapped with a curl of red ribbon.

"You didn't — I mean — you didn't have to—" Severus spluttered, suddenly awkward. He hadn't got her anything.

"I know I didn't. I wanted to. But don't get too excited, it's nothing much. Still…'tis the season. Go on, open it."

His long, pale fingers brushed her warm palms as he took the parcel. Delicately, he tore back the paper to reveal a pile of green knitting. He pulled it out, and the pile unfolded itself into a long, winding scarf.

"It's a bit crooked," said Lily apologetically. "I'm a terrible knitter. My mother's disgrace. I thought I'd try magic to make it easier, but it was still a lot harder than I expected." She laughed, a bit nervously. "But it's warm! I know how cold those dungeons get…and I thought it might be nice to have something warm…I may have skipped a few stitches, so it's a bit sloppy…" She was rambling, and he was tempted to let her carry on because her desire to please him was so charming, but she kept glancing at him anxiously, and his sympathy stirred.

"I love it," he said, and he meant it.

She beamed. "Here." She took the scarf from his hands and draped it around his neck. It was very warm.

"How do I look?"

"Very dashing. Not at all like you're wearing a knitted abomination."

"It's wonderful. Thank you."

Lily smiled, and Severus felt that familiar, overwhelming warmth that only she enkindled within him. He ran his fingers over the crooked stitches. He wished he had something to give her.

"God, look at that moon." Lily had placed her hands on the window and was peering out into the grey dusk. "It's not a full moon tonight, is it?"

"No, it's waning gibbous," Severus responded automatically. He hesitated, a sudden idea appearing hazily before him. Should he tell her? She was his best friend in the world. They told each other…well, not everything…but a lot of things. "What do you think is going on with Lupin?" he asked, before he could change his mind.

Lily blinked, turning away from the window. "How do you mean?"

"He missed Ancient Runes again this week."

"So? He was ill."

Severus responded with a skeptical snort.

Lily raised her eyebrows. "What, you don't think he's ill?"

"I think…" Severus took a deep breath, preparing himself. "I think he's a werewolf."

Lily stared at him, her mouth slightly open. Then, she did something horrible: She burst out laughing. "You think he's a what?"

"A werewolf," said Severus impatiently.

"You're joking."

"No, I'm not. I've been tracking his disappearances, and it's always on the full moon. The full moon, Lily! You think that's a coincidence? And then he shows up in class the next day with fresh cuts and scratches…"

"He's ill, Sev…"

"Then how do you explain the scratches?"

"I'm sure there's some Wizarding disease that causes scratches."

"Yes," said Severus. "There is. It's called Lycanthropy." He watched her, almost hungrily, as if he could force her to see reason by the sheer ferocity of his gaze. A small wrinkle creased her brow. She was thinking it over.

Then she shook her head. "Remus Lupin is not a werewolf," she said bluntly. "That's ridiculous. And frankly, even if he were, I don't see why it's any concern of yours."

"I think I've got a right to know if there's a werewolf running around school!"

"Well, I don't. If he were a werewolf — which, come on, Sev, he's not — but if he were, then I would think that's his own personal information to share with whomever he pleases, and no offense, but I don't think that includes you. I mean, you don't see me trying to bully Peter Pettigrew into admitting he's a vampire."

"Very funny."

"Although, I do think we could make a plausible case for Potter being a Dementor…"

Severus smiled in spite of himself, in spite of the gloomy disappointment seeping through his whole body. This was not the reaction he had desired. He'd wanted her in on the hunt, on the quest to prove his theory, his quest for revenge. Instead, she'd scoffed.

Lily was watching him with a small frown. "I've got to get to dinner. I'm supposed to meet Anson. Are you coming?"

"No," he said, turning back to the window. What did she have to bring up her stupid boyfriend for? "I'm not hungry."

"Sev..."

"Happy Christmas, Lily," he said shortly, and he left her standing alone in the glimmer of light from the waxing gibbous moon.