The Marauders celebrated their reunion by working extra hard on the map. By the end of February, the map outlines and labelling of the entire castle was finished. But the plotting of humans inside the castle proved to be an uphill task.

Remus, who was by far the best in Charms among them, was naturally given the responsibility to master the series of complicated charms needed to finish the map.

Remus was spending a lot of time in the library these days. Apart from studying for the OWLs, he looked up every book of Charms he could find.

Finally one day he found a set of three thick books which contained instructions related to their job. He stuffed them inside his bag and hurried out of the library. Knowing that his friends would be under their trademark tree, Remus walked towards the exit of the castle. Suddenly his bag split under the strain of the books inside, scattering all his belongings on the floor.

As he was picking them up, he heard a familiar voice.

"—thought we were supposed to be friends? Best friends?" Snape was saying.

"We are, Sev, but I don't like some of the people you're hanging out with. I'm sorry, but I detest Avery and Mulciber! Mulciber! What do you see in him, Sev? He's creepy! D'you know what he tried to do Mary MacDonald the other day?" asked Lily.

Remus realized that they hadn't seen him; the pillar against which Lily was leaning was blocking him from their view.

"That was nothing. It was a laugh, that's all..." said Snape.

"It was Dark Magic, and if you think that's funny—"

"What about the stuff Potter and his mates get up to?" said Snape, resentment evident in his voice.

Remus crouched in the shadows, listening quietly.

"What's Potter got to do with anything?" asked Lily.

"They sneak out at night. There's something weird about that Lupin. Where does he keep going?" demanded Snape.

For a moment Remus felt apprehensive, then he heard Lily say, "He's ill. They say he's ill—"

"Every month at full moon?"

"I know your theory," said Lily coldly, and Remus felt a sudden affection for her. "Why are you so obsessed with them anyway? Why do you care what they're doing at night?"

"I'm just trying to show you they're not as wonderful as everyone seems to think they are."

"They don't use Dark Magic, though," said Lily, dropping her voice. "And you're being really ungrateful. I heard what happened the other night. You went sneaking down that tunnel by the Whomping Willow and James Potter saved you from whatever's down there..."

"Saved? Saved?" spluttered Snape. "You think he was playing the hero? He was saving his neck and his friends' too! You're not going to—I won't let you—"

"Let me? Let me?" said Lily fiercely, using the tone she always used on James and Sirius.

"I didn't mean—I just don't want to see you made a fool of—he fancies you, James Potter fancies you! And he's not—everyone thinks...big Quidditch hero..." Snape's hatred was rendering him incoherent.

"I know James Potter's an arrogant toerag. I don't need you to tell me that. But Mulciber and Avery's idea of humour is just evil. Evil, Sev. I don't understand how you can be friends with them."

Lily and Snape were walking away. Remus stood up with his bag .Then he darted off to find James, though he knew it had been wrong to overhear Snape and Lily's disagreement and even more wrong to repeat it to James. But he wanted to uplift James' mood, which kept going down for days every time Lily rejected him.