Remus found Lily sulking in a back corner of the library, pretending to read a book on healing potions. "You do realize we don't take our N.E.W.T.s till next year, right?" he said, coming up behind her.

Lily jumped at his voice. "Oh, God, Remus," she muttered, glancing up. "Did James send you here?"

"No," said Remus, which was true. "But I am here about him."

Lily sighed. "Remus, I do not want to listen to you defending your shitty friends right now."

"I just need you to come with me. I've got to show you something." Remus's heartbeat was pounding in his ears—he knew he'd never be able to take back what he was about to do, even if it all went terribly wrong, but he had to do it anyway. After everything James had done for him, he owed him this. "I think you'll find you've got James all wrong."

"I think I very much will not find that."

"Please, just come with me, Lils. It's—it's about the secret James was keeping from you. A secret all the Marauders have been keeping for a very long time."

Lily pursed her lips; Remus could see the battle between pride and curiosity playing out behind her eyes. As he'd expected, her curiosity won out. "Where are we going?" she asked him, standing up with a sigh.

Remus gave her a thin smile. "Come on."

He led her back to Gryffindor Tower and up the stairs to the boys' dormitories. "You're taking me into your room?" Lily asked.

"Needs to be somewhere private," Remus explained. "The others should already be inside."

He pried open the door to the Marauders' room to find that he was right: his three roommates were seated by the bay window, attempting to cheer James up with a game of Exploding Snap. James's eyes went wide as Lily stepped inside behind him.

"What's she doing here, Moony?" Sirius asked.

"I'm going to tell her," Remus said.

"Tell her what?"

"You know."

"Oh." Sirius rose to his feet, as did James and Peter beside him. "Shit."

"You don't have to, Remus," James said quickly.

"I want to." Lily would understand—she was his friend, and had been for years. He could trust her.

Remus turned back to face her, took a deep breath, and promptly began to pull off his robes.

Lily blinked at him, startled. "Remus, what in Merlin's name are you doing?" She frowned as he tugged off his shirt. "Are you getting naked in front of me?"

"Only partially." Lily's eyes flicked down to the scars than marred Remus's chest—he knew she'd never seen them up close before, red and deep and angry. But he gestured to direct her attention to his biceps instead, where his bite was.

Lily paced in a slow circle around him to take in the nasty teeth marks from the bite. "How did you get that?" she asked quietly.

"Fenrir Greyback," Remus replied.

Lily stopped. "Fenrir Greyback. Fenrir…." She raised a hand to her mouth as the truth hit her. "Oh, my God. Severus was right."

"He was." Feeling a wave of cold creeping over his skin, Remus grabbed his shirt and slipped it back on. "I'm…I'm a werewolf, Lily."

"A werewolf." Lily worried her lip, taking a small step back. She didn't look scared or angry, though—just very, very surprised. "How—how long?"

"Since I was four years old."

"Four years old? So that means—"

"Yes, I was bitten before I started here. Dumbledore arranged for me to spend the full moons inside the Shrieking Shack so I could safely come to school. That's why—why the Shack shrieks sometimes. It's not ghosts or spirits, it's…me. The wolf, I mean."

"The Shrieking Shack…." There were tears in Lily's eyes now. "Oh, Remus. I had no idea. That's terrible, the pain you must go through every month…."

"There's a lot of pain," he admitted. "The wolf attacks itself if it doesn't have anything to feed on. That's how I've gotten so many scars." He glanced over to the other Marauders. "But they found a way to make things better for me. They figured out the truth back when we were second years, and I—I thought they were going to have me kicked out of the school. But instead, they wanted to keep me company during my transformations, keep me from tearing myself apart every moon. So they began the work to become Animagi." Remus smiled at his friends. "It took them nearly three years to do it—I assumed they would have given up long before. But they never did. And early last year, they finally pulled it off."

"You can't be serious," said Lily. "Becoming an Animagus isn't something a fifth-year student could do."

"Depends on the fifth year," Sirius replied. With a nod to Remus, he transformed himself into a dog, sprouting his shaggy black fur and giving a long, lazy stretch. Lily made a startled little noise at the sight of it.

James and Peter transformed too, and stag-James clopped over towards Lily, flicking his ears at her. "Bloody hell," she whispered. She reached out to touch James's head as if to make sure he was real.

"The whole process was extremely dangerous, especially since they had no one to help them," Remus continued. "A couple of times, I begged them to give it up. But they didn't listen, because they all knew how badly I needed them." The Marauders changed back into their human selves, with James now directly in front of Lily. She met his eyes. "Now when the full moon comes, they are there by my side, saving my wolf from itself every month. I don't know what I'd do without them." He nodded to Lily. "That's why James can't go with you to Slughorn's party—because it's the night of the next full moon. He'll be in the Shrieking Shack with me, like he always is. He…he cares so much for you, Lily, but he couldn't tell you the truth because the truth wasn't his to tell. It was mine."

Lily shook her head, still looking at James and appearing entirely overwhelmed. "Well, now I feel bloody rotten," she said at last. "For telling you off like I did."

"Oh, don't worry," James assured her. "I'm sure I deserved to be told off for something." His eyes shifted to Remus; thank you, they told him, bright with shock and gratitude. Remus nodded.

"You can't tell anyone," Sirius said from behind them. "Remus would lose everything if you did."

"Of course I won't," Lily said quickly. She moved to stand at Remus's side, tugged on his sleeve affectionately and stretched up to brush a kiss against his cheek. "Thank you for telling me," she murmured. "Your secret's safe with me, I swear it."

"I trust you," Remus said. "I'm sorry I didn't tell you earlier. It's just…difficult for me. You're the first person I've actually told, really."

"No need to apologize," Lily assured him; "I understand." Smiling a little, she spun a strand of hair around her fingers. "I really should get going, though. Mary will be wondering where I am—I promised her I'd show her Avelio if James managed to teach it to me."

"Remember the swish," James told her. His eyes had gone down to her lips.

"I will." James and Lily spent a long, charged moment taking in every aspect of the other's face, as if somehow they were seeing each other for the first time. Then Lily turned to leave, James's eyes fixed longingly on her bouncing red hair as she retreated to the door.

Lily stopped suddenly on the threshold and looked back to him. "My Patronus is a doe, you know."

"I know."

"What a strange coincidence, huh?"

James's lip quirked up. "Quite strange."

Lily raised her eyebrows at him, a thousand possibilities flickering across her face; then she spun back around and walked out, closing the door gently behind her.