1Disclaimer: I don't own anything you recognize.
James watched Lily in awe as she put more ingredients into the cauldron. He couldn't believe that Lily Evans, teacher's pet extraordinaire was in Myrtle's bathroom in the middle of the night concocting a potion. Wondering what could make 'Perfect Lily' sneak around at two o'clock in the morning, James moved closer to the cauldron. He cursed silently when he accidentally kicked an empty ingredient jar on the floor.
"Is someone there?" Lily asked, looking frantically around her. She looked right at James, and for a moment, he was afraid she could see him through the invisibility cloak. After a moment of listening and not hearing anything, Lily continued to add ingredients to the cauldron. After a few minutes, however, even James was surprised as Remus and Sirius snuck into the bathroom.
"Evans, what are you doing out of bed?" Remus asked curiously. He had woken up about five minutes ago, only to find James's bed empty and the invisibility cloak gone. He promptly awoke Sirius and told him what had happened. He had contemplated waking Peter too, but Peter was so afraid of getting caught doing something against the rules that he would probably get them found.
"I-I-I..." Lily stammered guiltily, hiding a bottle of some pink liquid behind her back.
"Tell me, what would make the wonderful Lily Evans sneak around at night?" Sirius asked with a smirk. "You're not doing something you shouldn't be doing, are you?"
"Just go away, this is none of your business," Lily pleaded. James took off the invisibility cloak and cleared his throat. Lily gasped as she saw him.
"What are you doing?" he asked.
"That's none of your concern, James Potter!" Lily insisted. "Now, go away before you ruin the potion. It has to be done just so, and if you make a mistake, the consequences can be horrible."
"Uh-oh boys," James said with a smirk. "We better leave. We wouldn't want anything horrible to happen, would we?" Motioning to the others to follow, he exited the bathroom. As soon as they were outside the door however, all three of them got under the invisibility cloak and went back in. They saw Lily stand at the cauldron for a moment, go to the door to see if they had indeed gone, and, not seeing them anywhere, go back to the cauldron. She pulled the cork out of the bottle she was hiding, and began to pour the pink liquid into the cauldron. All of a sudden, white smoke started billowing from the cauldron and made all four of them cough and choke.
When the smoke cleared, the boys pulled off the invisibility cloak and looked at Lily, who was wide-eyed with terror. She glared at them before she stopped short and said, "Where is the cauldron? And why is it daylight already?"
All of a sudden, Myrtle came out of one of the stalls. "Ooh, are you in trouble now," she said, and then began giggling uncontrollably.