Disclaimer: I don't own Harry Potter
The dungeon door closed, drowning the room in near-darkness. Their hearts beat fast, the lack of light a thankful disguise for their blood-laden cheeks. Lily opened a cabinet and rearranged the vials and various ingredients as an excuse to hide her face, to slow her rapid breathing, to will the blood out of her face.
Remus quickly walked around the whole Potions classroom, going from cauldron to cauldron, trying to distract himself from his best friend's girlfriend. He had liked her for years, ever since his first day at Hogwarts.
It was a minute until his last full moon of Hogwarts. Now or never.
As Lily stood up, she was aware that her one of her boyfriend's best friends was right behind her. Her feelings for him had been lost among her loyalty to her, as of last night, fiancé, but were present none the same. The ring on her finger seemed like a millstone, a combination of regret and desire rising like bile in her throat. His hand was on her shoulder, a gentle yet firm grip that turned her around. Remus, now face to face with Lily, stayed silent for a second or two.
Then their lips met.
It started a small, restrained peck, both of them not wanting to betray James but still satisfy themselves. After about 8 seconds of calm, almost clinical, pecking, the wall between then tumbled down. Their tongues caressed, a wild, animalistic passion running through their veins. This overt osculation was something scarcely known to either of them, Lily usually pulling back when with James, and Remus having little-to-no attraction to most others.
His face began to transform and become more wolfesque. Noticing this, Lily pushed back in shock. Remus hid in shame, not wanting her to know that he was a werewolf. Their gazes locked, and his last thought before his transformation: Protect Lily.
He hurdled out the door, bones shifting in his skin. Lily attempted to run after him, but, needless to say, could not. He ran out of the castle, finding Wormtail, Padfoot, and Prongs. As the mouse ran through the flying branches of the Whomping Willow, he refused eye contact with the stag to his left, out of shame and, unbeknownst to Prongs, betrayal.
Back in the dungeon, she slid down the door, tears in her eyes. She had lost control and now she had hurt herself. Again. As the tears slid fruitfully down her cheeks, her weeping filled the stone room as one regret encompassed her mind like a fist.
She had just kissed goodbye the love of her lie of a life.