Just in case you don't know what Machiavellianism means:

Mach·i·a·vel·li·an
–adjective
1. of, like, or befitting Machiavelli.
2. being or acting in accordance with the principles of government analyzed in Machiavelli's The Prince, in which political expediency is placed above morality and the use of craft and deceit to maintain the authority and carry out the policies of a ruler is described.
3. characterized by subtle or unscrupulous cunning, deception, expediency, or dishonesty: He resorted to Machiavellian tactics in order to get ahead.

Or in other terms: term that some social and personality psychologists use to describe a person's tendency to deceive and manipulate others for personal gain.

I just soooo wanted to use it in a story.

Lily Evans was not a happy camper. Her friend Alice had just locked her in a broom closet and said with a cheery smile, "I'll be back with a surprise Lily!", and if Lily knew Alice at all, she knew what the surprise was. The door to the broom closet flew open and a body was thrown in and the door slammed shut again. Outside the door, Lily could hear Alice and the Marauders laughing. "I'm putting a silencing charm and a jinx on the door, Lily! You can't get out until I let you out-" Alice said.
"-And we don't plan on doing that till tomorrow morning at least." said Sirius, doing a bad job to surpress the glee in his voice.
Lily muttered something incoherent and looked at her watch. It was 2:45. How was she going to last? As if her captors had read her mind, Lupin said:
"We've put food in there, and if you need light theres always your wands." Lily heard Sirius putting the charms on the door, she turned to the body in the closet with her.
"Did you know about this?" Lily asked with anger in her voice.
"Are you mental?" the body replied, "Like they'd let me know I was being locked in a closet with you, Sirius would think it was funny"
"Sirius' jokes aren't very amusing." said Lily.
The body shrugged. Lily took out her wand and muttered 'Lumos'. The tip of her wand lit up and spread light to the entire tiny closet. She could see the bodies face now. His untidy hair was neater than usual and with the addition of the light he was looking at Lily's face, searching it hungrily.
"Forget it, Potter." said Lily defiantly.
"Forget what?" James replied, snidely. "I didn't say anything"
"Your face suggested it." said Lily.
James shrugged this off. "So what are we supposed to do in here"
"I think my friends and your friends have a very good idea of what they want to happen in here." replied Lily nastily.
"So why deny them the pleasure of being right?" James taunted softly in her ear. Lily jumped, she hadn't seen him move closer to her.
"C'mon Evans. I know you like me." James persisted.
"You have no proof of that"
"Don't I? You've been staring at me all week, and," James paused for a second, "You kissed me"
"James! You know very well we ran into each other!" shouted Lily turning to face James who took advantage of the opportunity.
He pressed his lips to hers so suddenly it took Lily a minute to work out what was happening. James pressed Lily up against the wall of the tiny broom closet and pulled away. Lily looked at him, shock written across her face. "What's a matter?" he asked softly, "Didn't want me to stop"
Lily regained herself and put on a fierce expression. James took no note of this and waited for her to speak.
"That's Machiavellianism!" she shouted.
James laughed. "Why are you using big words? Besides, no it wasn't. I didn't manipulate you, you were just as eager to kiss me as I was to kiss you"
The corner of Lily's mouth twitched slightly but she held her expression.
"Aw. come on, Evans." He was at her ear again. Lily shuddered invoulantarily as she felt his warm breath on her skin. "You know you enjoyed it"
"That's got nothing to do with the point at hand." Lily said softly.
James could tell she was giving in. "Maybe not, but it's a point I feel I need to make"
Lily didn't answer and James took the opportunity to kiss her again. Lily didn't protest, but she didn't embrace the kiss either. James put his hands down around her waist and Lily's hands found her way to James' tie and untied it. James pulled away, laughter dancing in his eyes. "Are you sure you want to go that far Lily?" he asked softly. "What about your boyfriend"
"B-Boyfriend?" Lily asked. She racked her brains. "I don't have a boyfriend"
James laughed. "I was talking about Snape"
Lily looked at him. "I don't like Snape"
"But he likes you." said James, all laughter gone now.
Lily looked at James. She could tell he didn't like this fact much. "I don't like Snape." Lily said sternly. "He's my friend"
"He wants to be a bit more than friends." James replied with a look of disgust.
"Well, I don't." said Lily with a voice that said the conversation was now over.
James looked at her. "I want to ask you a question"
"What"
"Who do you like"
Lily turned a bright shade of red. "What does it matter"
"Well, if your in a broom closet doing, god knows what, with me and this bloke likes you back, I want to make sure he can't put me on my death bed"
Lily laughed. "I like a certain person." "Really now?" asked James jokingly.
Lily pushed this comment aside. "He's in my house." she said, getting closer to James. "He's got this black hair thats never neat, always with the same three people." Lily was unbearably close to James now, and with the expression on his face that he was battling inside his head, Lily knew he couldn't stand being this close to her and not have her.
"His name's James Potter." she whispered in his ear. James looked into her brillant green eyes, studying her face. He'd had enough. He picked Lily up off of him and pushed her against the wall, pressing his lips to hers. Her fingers found his messy hair and wound their way into it. James began to unbutton her shirt and-
BAM!
The broom closet door opened and standing there was known other than Snape and Sirius.

"Oooh. Did Jamsie get a little." Sirius taunted.
"I thought the door was locked?" James demanded.
"Only from the inside." said Sirius roaring with laughter at the look on Snape's face. "What's he doing here?" James asked Sirius again.
Sirius wiped a tear from his eye. "Got detention trying to hex me. Needed cleaning supplies"
Snape took in the sight of Lily's shirt half undone and James' tie untied. Lily got up, and re-buttoned her shirt, not looking at Snape or Sirius. Snape grabbed a mop. "Ah, what's the matter, Evans?" asked Sirius.
Lily just looked at him. James was half afraid for Sirius' life.
"Yhea, Evans." said Snape nastily, "You were snogging Potter a second ago, why don't you snog Sirius too? Filthy Mudblood"
She looked at Snape then got up and walked over to Sirius and pressed her lips to his. Sirius was slightly shocked and didn't know what to do. Snape was furious and when Lily pulled away, showing an extremely confused Sirius she said:
"It's much better kissing him then kissing a Death Eater liked you"
Snape turned away and left. James looked at Lily in awe and Sirius still stood there shocked.
"Y...You kissed me?" Sirius stammered. "Don't get used to it." she said. "Now, I've got some unfinished business to attend to." She grinned and shut the closet door in a very confused Sirius' face.

Sirius is win. xD