Disclaimer: I don't own anything, so you'll need to find other fodder if you wish to sue. Oh, and flames are accepted/welcomed. They'll be used to roast marshmallows later on.
Poisonous
Snape pulled away from the kiss and sat back down on the sofa, picking up his glass of wine. He crossed one black-robed leg over the other and sneered disgustedly at his visitor.
"Now surely, you didn't come all the way here just to do that, did you? All the way to my disgusting muggle dung-hill, as you so eloquently like to call it? As much as I don't doubt that my good looks," he said, bemused, "can be spotted from miles away, something is telling me you have an ulterior motive. Am I right, Trixa darling? Or have you regressed back to our Hogwarts days, playing the part of the common whore for your own," he took a sip of wine, black eyes boring into hers from above the rim of his goblet, "sick pleasure?"
"Funny you should mention Hogwarts, Snivelus. Considering your reputation, I'm surprised that that muggle-loving idiot ever took you back, considering what you've done!" She smiled at him, as if admonishing a young boy. "Not to say, of course, that your actions weren't admirable or useful, of course. But you've hardly" her eyes gleamed red in the light coming from a dusty fireplace, "suffered for the Dark Lord, have you? Whereas I, Rodolphus, Rabastan…" She paused, thinking. "Even that idiot MacNair, have all spent time in Azkaban, braving the Dementors, staving off death because we knew He'd be back someday!"
Bellatrix's eyes were manic, dancing about the dingy room, catching Snape's. She realized with mounting excitement that, for the first time that evening, or ever to her knowledge, Snape's eyes held something more than cynicism and disgust: fear.
Suddenly, Bellatrix felt a white hot pain jolt through her left forearm. Snape noticed: he reached for his wand on the table and pocketed it, realizing that Bellatrix had grown distracted, looking around as if she expected someone to Apparate at any moment. The gleam in Bellatrix's eyes suddenly disappeared and Snape realized that her wand was gone from the tabletop as well…
"Ms Black, please pay attention! Ten points from Slytherin!"
The voice snaps seventeen year old Bellatrix Black out of her reverie, as she hears several of her fellow Slytherins groan. They're dangerously close to losing the House Cup at this rate, but Bellatrix Black has other things on her mind: the newly acquired brand on her left forearm, for one. She keeps reliving the night before in her mind, over and over. The glorious, sensual pain of being branded one of the Dark Lord's servants and the exhilaration of knowing that she would kill, and soon, were enough to make her forget about such trivial things as the House Cup and History of Magic lectures. As the rest of her class files out of the room, Severus Snape, a friend of her boyfriend Rodolphus approaches her and touches her left fore-arm lightly.
"You too, huh?" he murmurs, looking almost ashamed.
She raises her nose disdainfully, and whispers, her voice poisonous: "I am proud to be a servant of the Dark Lord. And you should be too."
Without another word she walks off, knowing that the time would come where she herself would kill Severus Snape on the Dark Lord's orders. She only hoped that before that time, she'd get to have a little fun with him first.
Before Snape could do anything, Bellatrix had his hands bound between coils of razor-wire with a flick of her wand. Her voice was poisonous, the same way it had been on that afternoon, years before:
"He knows, Snape. And he's sent me," she smiled, and paused, enjoying the patterns that Snape's blood had started to make on the creaking wood floor, "to finish you."
He opened his mouth to speak, but she cut him off before he could say a word.
"I don't know what you were thinking, Severus. To be honest, I thought you had it in you. You were willing enough, certainly clever enough and yet, true to your nature, you decided to make life harder for yourself. You became a spy for that…that…" She trailed off, realizing that she couldn't even begin to describe the hate she harbored for the muggle-loving Mudblood sympathizer.
"Dumbledore," Snape whispered, each syllable venomous.
Bellatrix smiled.
"Yes, that. But I'm not going to kill you, Severus," she said sweetly. "I'm going to watch you crash and burn."
She took a sweeping look at the room around her, and then waved her wand.
"Incendio!"
The furniture and flooring around Snape caught fire, the flames licking at the wall, dangerously close to him. Bellatrix made her way to the door, smiling wickedly. Standing in the threshold, she grinned at Snape, whose face remained passive, watching the flames quickly surround him.
"You make me sick, Severus."
She put her hood back on, looking almost longingly at the pale face half-shrouded by black hair. Her eyes glowed red in the firelight.
"Crucio."