Author's Note: Thank you for your reviews! I'm still working on fleshing out this story, but I'm hoping to update it once a week. I'm really excited to work out the dynamic of the Marauders sans Remus, which I think would be a far more imbalanced one.

Mercury Lies
Chapter 1: to constitute

Friday morning, four weeks after McGonagall had approached him, found Remus and Pettigrew in the library, half-way through their lesson. In the last four weeks, they had had twelve lessons; two, sometimes three times per week, Remus's Prefect schedule allowing. Remus enjoyed teaching Pettigrew, who had proven himself to be an attentive student. During today's lesson, he was practising his animal to object transfiguration on the same matchbox Remus had given him before.

With a look of intense concentration on his face, Pettigrew pointed his wand at the matchbox and made his wand movement, carefully, precisely. And when he tapped the lid of the box, it wriggled a little and, right before their eyes, grew in size, like a fast-growing plant, growing white and brown fur, small teeth, and black eyes, which glittered in the brightly luminous library light above the table. And just like that, the matchbox had turned into a miniature dwarf hamster.

Pettigrew's eyes bulged comically for a moment, and then he looked up at Remus, his mouth hanging open. Then, he let out a victorious whoop. 'I've done it!' he told Remus at a volume that was just on the edge of shrill, making Remus – who was already feeling more sensitive to sounds, with full moon coming up – wince a little at its intensity.

Pettigrew seemed not to notice, his voice going a mile a minute. 'I can't believe – never thought I would – I mean – you're absolutely brilliant, Lupin! – shall I just – I mean, I have to give you something – would you like anything from Honeydukes? You've said you're not going to Hogsmeade this weekend –'

Remus blinked at him, surprised. He hadn't thought Pettigrew would've remembered, but it was very kind of him to. He smiled. 'Congratulations. And you don't have to get me anything. Maybe get Gloria something, though.'

Pettigrew's cheeks flushed red, but he was grinning. Over the course of their sessions, he had shyly confessed to Remus that he had a crush on a girl in Remus's year, called Gloria Atterberry. She was a Hufflepuff, with a heart-shaped face and beautiful, sky-blue eyes, and she had been making eyes at Pettigrew from across the Great Hall. According to Pettigrew, that is. He had also confided in Remus that it was the first girl he'd ever fancied, and that he hadn't told his friends yet. When Remus had asked why, Pettigrew had raised an eyebrow, and muttered something about Sirius always asking how big her tits were, which had made Remus laugh.

'Right,' Pettigrew responded.

Remus nodded politely at him. 'I think that's it for our sessions. If you have any more questions, I'm mostly in the library when I'm not in class. Find me any time.'

Formally, Pettigrew shook his hand. That Monday, in class, Pettigrew not only successfully transfigured his wooden box into a hamster, but he was also able to explain to the class the theory behind it. The very same day, he sent Remus a box of the most expensive Honeydukes chocolate he could afford, and a note that explained all this and had the word "thanks" underlined four times. Sat on his bed in the Hospital Wing, hidden behind a thick white curtain, Remus smiled, and snuck a piece of dark chocolate out of the box when Madam Pomfrey wasn't looking.

Remus was back in class a few days later, and after his first Transfiguration lesson, Professor McGonagall asked him, again, to join her in his office. Over a cup of tea, she complimented him warmly. 'I've seen excellent results with Mr Pettigrew. He has progressed nicely. His wand work, especially, has become a lot steadier. I award you twenty points for Ravenclaw and my compliments.'

Remus, who had only ever been given McGonagall's compliments once before in his second year, felt his cheeks heat up, and hastily busied himself with his tea. He would later argue to himself that the only reason he agreed to teach his fellow Prefect, Lily Evans, about Switching Spells was because of those bloody compliments (and, perhaps, his innate need to please his Professors).

His first lesson with Lily Evans, whom he knew only from having occasionally being assigned to patrol with her, was that Sunday. She met him in the library, perfectly on time, and her arms laden with books and notes about Switching Spells. Over the course of the lesson, it showed clearly that she was very clever and very sure of herself when it came to the theory behind Switching Spells, which she knew the same way Remus knew MacKendrick's The Greek Stones Speak: The Theory of Archaeology in Ancient Greece: by heart. In practice, however, this mattered little.

Her wand work, although flawless in its movements, lacked finesse and precision, two things that should've been addressed within her third year, but had somehow been overlooked. During the end of the lesson, Remus told her, softly, that she was performing below OWL standard. And before he could say anything more, Lily Evans, with her beautiful, dark, red-orange hair, started crying.

'It's just so hard,' she said softly, her green eyes overflowing with uncharacteristic tears that landed onto her detailed notes, blurring the ink. Remus sat, frozen, opposite her. 'I've been trying my best at Transfiguration, but it's just so wishy-washy,' she continued. 'Focus on your wand movement,' she sneered, in a perfect imitation of Professor McGonagall. 'What does she think I've been trying to do?'

Remus bit his lip, hesitating ever so slightly, but then stood up, and slid into the seat next to her. He put a warm hand on her arm, pulled his favourite, blue check handkerchief out of his pocket, and offering it to her. Lily took a few shuddering breaths, and wordlessly took it out of his hands, dabbing at her face.

'I'm sorry,' she said, softly, avoiding looking at him.

Remus just said, 'There now. Don't cry,' and the smile she offered him when she met his eyes was beautifully grateful.

His lessons with Lily were very different than his lessons with Pettigrew. Even after only five lessons, she was showing steady progress, which was likely due to her approach, which was a lot more serious and no-nonsense that Pettigrew's. She preferred to spend the lesson working on her wand technique, and only tended to talk about non-academic subjects when Remus declared their lesson to be over for the day.

Presently, she had just finished packing her bag, which she slung over her left shoulder with practised ease. 'Have a good weekend, Lupin,' she offered, looking down at him from where she was stood, behind the wooden chair she had previously occupied.

Remus looked up from where he was filing his notes into his folder, and nodded. 'Thanks, Evans. You too,' he responded.

'Lily,' she said, firmly.

'Lily,' he responded, giving a small smile. She gave a nod in acknowledgement, and left him sitting there, at his favourite table in the library. Remus watched her go, and then returned to filing his notes. He had bought a folder especially for his tutoring notes, which had been a necessary purchase, if a slightly frivolous one. He had taken many notes for Pettigrew, who had dutifully returned all of them, and he was also starting to take notes for Lily, jotting down titles she might want to check out or diagrams she might find helpful.

Because he had missed the last Hogsmeade weekend due to the full, he had placed an owl order at Scrivenshaft's for the folder and some new parchment paper, and had gritted his teeth at the three galleon price the tiny, speedy owl that belonged to the shop had come back with. He had actually also needed to buy a new tie, because this one had started to fray, but that would then have to wait until he got his Christmas money.

As he finished filing his notes and packing his bag, he caught himself wishing, a little wistfully, that he had enough money to buy whatever he wanted.

'Evans! Go out with me!' James shouted across the table, by way of greeting, that morning at breakfast. It was a dismal November morning, just two months into the new school year, and he had been feeling particularly cheerful this morning. Yesterday, the Gryffindor Quidditch team had smothered the Hufflepuffs in the first Quidditch match of the year, and their chances for winning the cup were steadily rising.

'Potter, shut up,' Lily responded, from where she was sitting next to Marlene McKinnon and Alice Featherston, neither of whom looked too perturbed by this behaviour. She hadn't even looked up from her plate.

'I happen to know for a fact you've got a free period tomorrow between Charms and Potions!' James tried again.

Lily grimaced. It was a commonly known fact that the reason they had a free period tomorrow was because Professor Trelawney had had some sort of nervous breakdown following an epic prank James, Sirius and Peter had pulled, which had resulted in the destruction of half of all her teacups. Trelawney had claimed she needed some more time to balance her inner eye.

'No, thank you, I'm busy,' Lily said.

'It's just a date, Evans, I'm sure you can make time.'

She heaved a big sigh, standing up from the table. James, who was thrown for a moment (she had never done this before), looked at her, his whole body thrumming with heavy anticipation. Instead of coming over to talk to him, however, she stood up and made her way over to the Ravenclaw table, where she sat down next to Lupin, who had been reading a heavy-looking book.

He looked up at her, surprised. She said something that involved a lot of hand gestures. Lupin looked up, catching James's eye, and then looked back to Lily, nodding and pushing his plate towards her. He made some sort of comment and she laughed, leaning over him to reach for the bread plate, and buttering her toast.

'Sorry, mate,' Sirius said, clapping James on the shoulder.

James's eyes narrowed at the pair of them.

That evening, an irrationally jealous James complained so long and so very loudly that Sirius was eventually persuaded to agree that, yes, there was something dodgy about that Lupin fellow, and yes, they would take turns keeping an eye on him whenever he would be tutoring Lily. All of this was decided upon in hasty whispers, when Peter was in the bathroom, because, as James put it, Peter was in love with Lupin, and his judgement could therefore not be trusted.

'The things I do to make you happy,' Sirius grumbled.

'You love me, really,' James responded.

Freshly washed, Peter appeared in the door of the bathroom. 'Are we planning something?' he asked, having caught the last two sentences, his eyes alight with curiosity.

'No,' Sirius said, shutting his bed curtains.

'Night, Pete,' James likewise said, leaving Peter standing by himself, quietly dripping water onto the dormitory floor. Eventually, he sighed, and got ready for bed. They would tell him eventually. They always did.