Severus kept his distance as he watched the four boys walking through the halls. He was getting sick of them, always pulling pranks or hexing him. He knew they probably would do something eventually to be expulsion worthy, but until then Snape had to actually catch them in the act.
The Marauders had turned a corner, and Severus was well aware that they could just be waiting around the other side to catch him by surprise, even though he was sure they weren't aware of his presence. Severus had been preparing for something like this however, and pulled a small mirror out of his pocket.
"Wingardium Leviosa," Severus whispered, and the mirror floated up to near the roof. No-one would have any reason to see it up there, and Severus could quite clearly see that the Marauders were still heading down the hallway. Sighing in relief, Severus turned the corner and continued following them, using the mirror to keep an eye on them.
Soon, the group was in an empty classroom, and Severus snuck up to the door, trying to listen in. Unfortunately, Snape couldn't hear anything clearly through the door. 'I'll have to come up with a spell for that,' said Snape, trying to figure out if he could sneak into the classroom undetected. Unfortunately, nothing came to mind.
Other students had walked past in the meantime, several of them whispering among themselves. Severus knew they were talking about him, looking shady outside a classroom, but he didn't care. Only the Marauders mattered, specifically getting rid of them.
"Hey Severus," called someone, and Severus jumped in surprise when he saw Lily hurrying towards him. "What you doing here?"
"Oh, ah, nothing," said Severus, getting up from the floor where he was trying to listen to them under the door.
"Why were you on the floor then?" asked Lily. "Is this anything to do with James and the others?"
"No…" said Severus, then saw the look Lily was giving him. "Maybe."
"Damn it, Severus," said Lily. "Can't you guys just leave each other alone for one second?"
"I will when he does," said Severus. "And the best way to do that is to get rid of him."
"Severus…" sighed Lily. "I really hope you boys will grow out of this silly feud one day. It'll probably be the death of us."
"Oh, please…" started Severus, as Lily began leading him away.
Meanwhile, inside the classroom…
"Is he gone?" asked Remus.
"I think so," said Sirius. "I just heard Lily's voice, so she probably led him away."
"Let's hope so," said James. "I'm pretty sure he's trying to find out what we've been up to."
"As if," said Peter. "He'll never find out about…"
"HUSH!" said Remus. "In case he hasn't left yet."
"Surely we'd know if he was still here," said Sirius. "Now we can get down to business. Has anyone discovered how to…"
"I thought we agreed we wouldn't discuss it out loud," said James. "Just because of the possibility that Severus might be listening."
"Or anyone, for that matter," said Remus. "Since, you know, what you've been planning is kind of illegal."
"Listen, what's the worst that could happen?" asked Sirius. "Besides, when we're older we could just say we decided to learn how to do it."
"Didn't McGonagall say you needed a reason to become one?" asked Remus. "What's your reason going to be?"
The other three were silent for a moment. "Guys, I think I found a flaw in our plan," said Peter.
"Idiots," muttered Remus.