AN: I get my ideas from mistakes other writers make. Plus, I don't own anything.
It was the end of October of their seventh year. While Lily had been furious to hear that James had been made Head Boy, their ample close contact due to shared dormitories and all the time spent working together had paid off for James. She finally kissed him at the end of September, although they didn't tell any of their friends.
The close quarters had proven handy when they decided to take the next step and become intimate with one another. Without worrying about their roommates walking in, their two singles quickly became one double and James' abandoned room across the hall, used only to house his clothes.
Because neither had told anyone about their new relationship, their friends were left to wonder why Lily was no longer short tempered with him, why she blushed when he made certain comments and why they often walked in the hallways together before and after classes. They figured that it was a matter of time before they made it official, having no idea that the pair had crossed the official line long ago.
One morning, Lily hadn't walked with James to Potions. She arrived early to class and was talking to Slughorn as the rest of the students arrived.
"I really wasn't surprised when they made you Head Girl. Even if you aren't from my house, I'm proud that such a fine student has been given this high honor," Slughorn gushed with a doting look on his face.
Lily, used to two months of compliments of this nature, knew how to act. "Well, at the end of last year everyone told me it was a sure thing but I--" James cut her off.
"Lily, your contraception isn't working."
Lily's eyes widened as she blanched and blushed at the same time, still looking at Slughorn. She slowly turned her head to face James who had taken a seat next to where she was standing. She had been staring at him incredulously for a few moments before James looked up and said "What?"
Stunned out of her silence, Lily lost her temper. "Are you serious? First, that is a very private thing to say to me in front of a teacher. Second, that is a very private thing to say to me in front of anybody at all." She was gesticulating wildly at each of her points. The class was watching avidly and Slughorn was blushing.
"Third, how would you know that? Of the two of us, you have not been so responsible thus far." Her cheeks were beginning to get red. Her breathing, now labored, served to further emphasize her point.
"Fourth, that was an extremely crude way of putting something of this matter. And fifth," Lily's eye contact with James broke for the first time since she turned to him, and only for a split second. "if what you said is true, we have bigger problems right now."
James was simply staring at her, lost for words. His reaction, clearly unsatisfactory to Lily, drew her wrath once more. "Are you going to say something?"
He stuttered in response. "T-that quill, the one you gave me. You said I never had to dip it. It's not working." He pulled a black pen from his pocket and laid it on the desk in front of him. Although he was clearly afraid of her, he kept staring at her, more afraid of what would happen in he looked away.
The color once again drained from Lily's face. Torn between her relief and her anger, she merely looked defeated.
"Trap." It was all she could say, but it was loud and completely clear. "Contraption." Had she not been holding her bag, she would have left it in the classroom. She turned and walked, emotionless until she reached the door where, as her fingers closed over the doorknob, her shoulders shook as she silently mouthed the word "trap" to the large piece of wood. The door clicked and every head turned to James, who clearly still did not know what was going on.
Sirius slid into the seat behind him. "So... When did you start shagging Evans?" he said coyly, breaking the silence in the room. A few giggles were stifled waiting for James' response.
"What do you mean? Who said that?" James asked, curious and frightened to how his friends figured out what he had been so careful to hide.
Remus, sitting at the table in front of him picked up the pen that was still lying on the desk in front of James. "Contraption" was all he said as he held the pen up clearly in front of his friend's face.
Pulling a Durex from his pocket, Sirius complimented. "Contraception," holding the condom at the same height.
"Which did I say?" James' voice broke as the blood slowly left his head. To his horror, it was Sirius who wiggled his hand.
All he said was "Bugger" as he bolted for the door, leaving his books, Lily's pen and a classroom of laughing seventeen year olds and one embarrassed teaching in his wake.