22nd October 1972

Peter Pettigrew had always prided himself on noticing things others didn't. He wasn't as loud or flashy as James or Sirius, nor as effortlessly brilliant as Remus, but he had a knack for details—tiny inconsistencies, stray words, the way people moved when they thought no one was looking. And right now, something was off about Remus.

It had started last year. Once a month, like clockwork, Remus would disappear. He never made a big deal of it, always muttering about illness or extra help from Madam Pomfrey. James and Sirius took him at his word, but Peter had always felt there was more to the story.

This time, he was determined to figure out why.

Peter had been watching Remus closely all afternoon, and sure enough, as dinner started and the Great Hall filled, Remus mumbled something to James about needing to see Madam Pomfrey and hurried off before anyone could question him further.

Peter quickly excused himself from the table and slipped into the corridors, making sure to stay out of sight as he followed Remus at a careful distance.

He ducked behind a suit of armour as Remus turned a corner, his heart pounding. He had to be careful; Remus was sharp, and Peter didn't want to get caught just yet.

Trailing someone through Hogwarts was a skill. He kept his steps light, his breath steady, his movements precise. He was always watching, always aware.

Remus moved with purpose, heading toward the hospital wing. Peter had expected that. What he hadn't expected was Madam Pomfrey waiting for him outside the doors, wrapped in a thick wool cloak. She didn't hesitate, just gave Remus a warm smile and ushered him forward. Then, after glancing down both ends of the corridor, she led him away—not into the hospital wing, but towards a narrow passage Peter had never seen before.

Peter pressed himself against the stone wall, hardly daring to breathe as Pomfrey flicked her wand. The concealed door shimmered into existence before swinging open. Remus stepped inside. The matron followed, and the door clicked shut behind them.

Peter clenched his fists.

For several long minutes, he simply stared. His mind raced with possibilities, each wilder than the last. He had expected another hospital visit, maybe some secret treatment, but this? A hidden door? A secret path?

He had to get closer.

Moving carefully, he crept to the door and pressed his ear against it, straining to hear.

Nothing.

Peter frowned. That wasn't normal. Hogwarts was old, full of enchantments and creaky doors and murmured voices through walls. But this one? This one gave him nothing. Not even the faintest hint of movement.

That didn't sit right with him.

His fingers twitched at his sides. He hated not knowing things, especially when it came to the people closest to him. He wasn't just the tag-along, the extra piece in their group—he contributed. He noticed. And right now, he was noticing that Remus Lupin was keeping a very big secret.

Taking one last look at the door, Peter sighed and turned back towards Gryffindor Tower.

If he couldn't figure it out tonight, he'd just have to be smarter next time.

And there would be a next time.

Peter couldn't let it go. The moment he returned to Gryffindor Tower, his mind buzzed with possibilities. He'd seen Remus disappear into that hidden passage with Madam Pomfrey, and the fact that there was no sound behind that door only made it worse. What was so secret that it needed to be completely sealed off from the rest of the castle?

He climbed into bed, but sleep never came easily when his thoughts were running wild. He stared at the canopy above him, trying to connect the dots. He had watched Remus vanish for over a year, each time returning looking like he had fought a duel and lost. Cuts, bruises, exhaustion—all conveniently explained away by illness or some incident that never quite added up.

He started paying even closer attention over the next few days. He wasn't obvious about it, at least he didn't think he was, but he made a point to sit near Remus in class, to keep an ear out for anything unusual. He noticed how, in the days following his disappearances, Remus always seemed to move a little more carefully, how he flinched slightly if someone knocked into him unexpectedly. How he had a habit of pulling his sleeves down past his wrists, even when it was warm in the castle.

…

The breakthrough came late one evening when the four of them were in the common room. James and Sirius were playing an intense game of wizard's chess, while Remus sat curled up in an armchair with a book. Peter was pretending to read his own, but his mind was elsewhere.

It was only when the firelight flickered across Remus' face that Peter saw it—the tiniest hint of a fading bruise near his temple. A fresh wound.

His stomach twisted. He leaned forward, keeping his voice casual. "You know, Rem, you've got more injuries than a Quidditch player, and you don't even play."

Remus stiffened slightly, but covered it well. "I'm just clumsy, Pete."

Sirius snorted from across the table. "That's a bloody understatement."

James barely glanced up from his chessboard. "Yeah, mate, I swear you trip over air sometimes."

Remus laughed along, but Peter wasn't convinced. He decided to push a little more. "It's weird, though," he mused. "You always seem to get sick or hurt at the same time every month."

There was a beat of silence. James and Sirius were too distracted by their game to notice, but Remus' fingers tensed around his book for the briefest second.

Then, Remus forced another chuckle. "I guess I have bad luck."

Peter smiled, but inside, his mind was racing. Bad luck didn't explain secret passageways, Madam Pomfrey's late-night disappearances, or why Remus never got sick any other time of the month.

No, there was more to it. He just had to put the rest of the pieces together.