Lily was true to her word.
By the end of the next week, Severus walked in on her in an empty classroom with her arms tangled in the embrace of a young man. They continued to kiss as the light from a window fell in on their hair and shoulders and seemed not to have heard the door open. It wasn't until Severus dropped his books in a flurry to pull his wand that the couple broke apart, and Remus Lupin looked around and flushed with embarassment.
"Pay him no mind," Lily said, pulling Lupin closer by the sleeve.
But Lupin couldn't take his eyes off of Severus's wand. It was aimed at his throat and above it, the black eyes glittered with an inhuman light.
"Sectum --" Severus yelled.
But Lily blocked the curse and turned to him with her fists clenched.
"How dare you try and use that on him!" she said angrily, red sparks firing from her wand. "How dare you!"
"How dare you kiss him!" Severus fired back, unreasonably.
Lily stared at him incredulously, "What, you won't date me so no one else is allowed to either?"
Lupin squirmed to grab his things, looking keen to escape from the room.
"Not so fast!" Severus cried, and Lupin fell hard onto his back.
"Leave him alone!" Lily cried angrily, and a golden light exploded from her wand.
Severus was blasted over the desks and against the door. He struggled to sit up, blood trickling from his hairline, as Lupin hurried from the room, looking guilty. He paused for Lily in the doorway, but her eyes were fixed on Severus as he pulled himself up, looking livid with rage. When it was clear Lily would not follow, Lupin hurried away.
"You don't want to do this," Severus warned her.
"Ha! I think you're the one who'd better back down," Lily told him. "I'm just as good as you in dueling."
"And other things too, apparently," Severus sneered.
"Oooo!"
A red jet of light shot toward Severus, but he ducked and it burned a hole in a nearby desk instead.
"You're so muddled from having your tongue halfway down Lupin's throat that you can't even aim properly!" Severus said in disgust, aiming a curse at Lily that locked her legs together.
She hopped on the spot, outraged.
"It would have been your throat I had my tongue down if you weren't so mean and nasty!" she growled back, and a blue jet of light made Severus's hands begin to slap his own face in a wild frenzy.
Lily threw back her head and laughed, but the action made her topple backward onto the floor and her wand rolled away. When she attempted to slyther after it, Severus stepped on it, but it was so bendy it didn't break; it merely lay squashed under his foot. He stared down at Lily through the constant slapping of his hands on his face, and she looked up at him.
"Am I really -- OUCH! -- mean and nasty? -- OW!"
"Yes, you are!" Lily fired. "I tried to ask you out, but you were so unkind! And then when I went with someone else, you tried to use the dirtiest spell you could think of on him!"
"But Lupin of all people? -- OW!" Severus demanded. "AH! Next you'll be dating Potter! -- OUCH!"
"Never!"
"Liar!"
"I am not! He's a bully and prat. I'd rather date the hideous caretaker!"
"No one would rather date the hideous caretaker."
They laughed.
"Well," Severus said reluctantly, "I can stand just about anyone except Potter -- OUCH!"
"Truce?"
"Truce," Severus said, rolling Lily's wand toward her arm with his toe.
Lily released herself of the spell, stood up, and brushed herself off.
"Hey!" Severus called when Lily brushed past him toward the door. "Aren't you going to -- OUCH! -- call this off? -- ARGH!"
Lily watched him a moment, smiling meanly.
"No," she said at last, "I think I'll take a leaf out of your book." And she marched from the room with her chin up, leaving Severus in anything but ecstasy.