Author's Note: Alright so this is for UnicornAndRainbows20089's Song-Fic Boot Camp (Prompt: Marshmallows. Song: So Anxious by Ginuwine), Gamma Orionis' Kink Challenge (Kink: Hair pulling), Ralinde's Pairing Diversity Boot Camp (Prompt: eerie/ eerily), and aimz666's The Ten, Twenty, Thirty Chapter Challenge (Chapter one title: Oh Sister of Mine). This is not Beta'd if you would like to offer your assistance please feel free to PM me.

Pairing: Bellatrix/Narcissa

Rating: M for Mature

Well, that seems to be all for now. Happy reading!

Oh Sister of Mine

Narcissa could feel her eyes, those eerily obscure violet eyes that set her body aflame. On the outside the seventeen year old was every bit the aristocratic, proper, pure-blood she had been raised as. But on the inside, far from prying eyes she was a quivering mess. Bellatrix was staring her down with those hooded bedroom eyes of hers. She did it with such a casual confidence and lack of caution that made Narcissa's stomach drop in trepidation.

She knew her sister and knew her well, when Bella focused all her attention on something it did not bode well for that person, creature, or otherwise. Even though the raw passion of her sister's stare perturbed her it also pleased her. Both emotions sat on opposite sides of the spectrum but oddly enough that wasn't the least of her problems.

Right now, Narcissa needed to get her mind off the intense stares her elder sister kept throwing her way without a care for the individuals seated around their dinner table. Beside her Lucius placed a hand on her knee beneath the table; squeezing it firmly in a warning – possibly to get herself together. He was obviously privy to her lack of decorum and wouldn't stand for her to make a fool of both of them.

-o0o-

Narcissa delicately cleared her throat, brushing her pale blonde hair off her bare shoulder. She had been left to mingle with the other women when Lucius was pulled to the side by her father. She was left to chat with Andromeda and some women she didn't know too well but because of the circumstances she would know quite well in a few moments. Andromeda stayed by her side much to Narcissa's relief despite the tension between the family and Andromeda. Her elder but much sweeter sister's choice in partners is what was pulling their family apart.

It was a shock that she had managed to attend this formal dinner, she looked a bit colder than normal but that was to be expected with the private on-goings in their family. The blonde stiffened when the back of her shoulder tingled, the hair rose on the back of her neck. Those eyes were back on her again.

"Sister…" Andromeda nudged her to catch her attention, lacing her arm through Narcissa's and leading them forward to continue mingling. There was an underlying of worry and the blonde did not miss the questioning gleam in her sister's eye.

"I am well, Dromeda." she assured her quietly, patting the other girl's hand with a stiff smile. "If you'll excuse me, I am in need to freshen up a bit." Narcissa nodded to her sister and the few women they had tittered with for the past fifteen minutes and made her way into the hallway. She took a breath before heading off to the nearest bathroom which happened to be down two long hallways and around a corner.

"My, my, little Cissy don't you look stylish tonight." Bellatrix seemed to materialize behind her without as much as a sound. She was leaning on the wall opposite of her holding a small bag of some sort and popping whatever the contents into her month. An absolutely salacious smirk crept onto her face, one which the blonde preferred to ignore.

She was looking the blonde over like she wanted to eat her. The long ivory sheath that hugged the blonde's slight frame was mouth-watering.

"Bellatrix," Narcissa greeted with a strained smile despite having taken fright at the sudden appearance of her elder sister and her compliment. She was not so dim that she could not see an insult for what it was. "What are you doing here?"

Bellatrix straightened, popping a tiny white ball of some sort into her mouth. It was produced from the small bag held in nimble hands. What was it that her sister kept consuming? Sugar cubes? No, Bella wasn't one for things too sweet and the thought of her consuming sugar itself was laughable.

"Why, I was just accompanying my baby sister to the bathroom." she cooed and it drew Narcissa attention to her soft lips. At least she assumed they were; they never looked dry and brittle so they must be soft and moist.

"I do not require assistance, Bellatrix." Narcissa drawled with a deadpan look directed at her dark-haired sibling. "However, I do want to thank you for your consid –"

"Oh, do not flatter yourself, Cissy." The older girl was suddenly in Narcissa's personal space, her hand slamming into the wall beside the blonde's head. She jerked away, inadvertently allowing herself to be cornered.

Narcissa's breath caught in her throat, what the hell was Bellatrix doing? The older girl's thick obsidian loose curls drew her attention to where they bounced lightly.

"Your mind is wandering, Cissy-darling." Bellatrix purred suddenly, shifting ever closer to her fair-haired baby sister. The scent of something sweet wafted around Narcissa, it swirled about her head and made her dizzy.

"What is it that you want, Bella?" she asked, priding herself in keeping her voice calm and steady. Even though her sister's proximity made her want to crawl out her own skin. Bella's nose skimmed Narcissa's delicate jawline with a soft hum.

"What I want?" Bellatrix repeated, her lips grazing the blonde's earlobe and watching the shiver travel through the girl's body. She brushed Narcissa's hair back of the girl's shoulder and lightly trailed her fingers along her collarbone.

Narcissa's heart picked up and was beating double time; she turned her head and tipped it up in a vain attempt to avoid her dark-haired sister's lips. "Bella, what are you–"

"Shhhh." Bellatrix hushed her, pressing into the teen. "So beautiful…fragile." she murmured, dragging her lips across the soft flesh of Narcissa's throat and drawing a soft groan from the teen. Her free hand grabbed at the blonde's hip, catching the silky material of her ivory dress and gathering it.

Narcissa was breathless now, feeling out of sorts at her sister's ministrations. All conscious thought of what they were doing being potentially wrong had flown out her mind when lips roughly captured hers.

The blonde squeaked, taken completely by surprise. She felt Bella's lips turn up in what she could picture was a condescending smirk. The hand at her hip was slowly dragging up the fabric of her dress. Inch by torturous inch milky pale and sinfully soft flesh was revealed. First delicate feet enclosed in gold heels followed by the smooth curve of a shapely calf. The material slipped over Narcissa's knee and danced over her thigh and stopped to bunch at her hip.

Bellatrix hummed appreciatively, trapping the material between their bodies so her hand was free to explore. Narcissa choked on a breath, and odd noise slipping past her lips. The dark-haired beauty blinked in surprise then grinned wolfishly. "Oh my," she purred, giggling darkly when her fingers parted bare flesh slicked with arousal. "Someone is naughty, hm? I didn't take you for one to skimp on her knickers, Cissy."

Narcissa's face flushed in embarrassment, now that her lips weren't attached to Bellatrix's she could think a bit clearly; despite where the other girl's hand was located between her thighs. Panic gripped her heart, just what were they doing? This was not suitable behavior for them, at least not out in the open.

"Stop, we can't do this." she murmured, not wanting to fight but she had to. How had they gotten so close to do this? Narcissa pressed against her older sister, attempting to push her away so she could get herself together but Bellatrix wasn't moving. "Bella, please move away from me. I don't want to do this, anyone could happen upon us."

The brunette's face darkened and a snarl twisted her lips – it should have made her unattractive in that moment but unfortunately for Narcissa that wasn't the case. "What did you say?" Bella hissed dangerously, her dark eyes burning the blonde's soul.

"We –" A shocked whimper stole away Narcissa's words, Bella's free hand had tangled in her hair skillfully and pulled. Her head snapped back into the wall, exposing her throat.

"You do not tell me when to stop or end things before I say so, do you understand me?"

Narcissa was quick to nod her head or at least attempt to do so but Bella had a strong grip on her blonde locks. Her scalp burned and tears gathered in the corners of her eyes. "Yes! I understand!" she cried out, bending her back and tilting her head further back to alleviate some of the pain.

"Good girl." Said Bellatrix, slackening her grip and slipped two fingers into Narcissa as a reward. The teen stiffened in surprise at the sudden intrusion, her thighs clamping around her sister's hand.

"Please…" The blonde choked out, taking hold of the other girl's wrist. Not here, not where someone can see. She wanted to say more but the words were stuck, leaving her only spit out one strangled word.

Bellatrix either didn't care for her pleas or wasn't listening because the fingers within her jerked, curling a bit and massaged her inner walls. The deceptively calm manner in which she did this almost ruined her. Narcissa's thighs parted, her body welcoming her sister's advances.

In that moment, with Bellatrix's fingers sliding into her repeatedly she felt like a common whore and it was exhilarating. Narcissa whimpered, her lower stomach quivering at the unadulterated ecstasy that lapped at her being.

There was a slow building heat that started at the tops of her thighs and crawled upward. That hand was back in her hair, yanking it back and tearing a small cry from Narcissa. "Listen, you belong to me. Do you hear me?" Bellatrix whispered harshly in her ear, her tongue swirling around the shell of it. A shudder wracked Narcissa's frame and she was teetering on the edge. "You. Are. Mine. No matter what that pompous disgrace of a Malfoy claims, do you understand?" she continued, her thumb slowly circling the bundle of nerves that made the Blonde swallow a scream.

"Yes…" Narcissa agreed frantically, bucking into the hand that was slowly undoing her. "I–I promise… please!" she cried, gripping Bella's shoulders tightly with her eyes screwed shut.

Bellatrix smirked, beholding the sight that was her baby sister. Taking in her flushed skin glistening with perspiration and the pleasurable agony written on her face. Her totally submissive nature seemed to come alive under Bellatrix's oppressive dominating ways. They way her reddened lips kept taking in tiny gasps of air clued her in to the blonde' impending release.

Finally she took pity on her poor sister and gave her exactly what she needed. The pace she set was brutal, not particularly caring whether Narcissa liked it or not. Instead she devoured the younger girl's lips, continuing to plunge her finger into the more than welcoming wetness. Narcissa could taste a milky sweetness on the other girl's tongue, reminding her of marshmallows.

She drank in her sister's small groans and cries of ecstasy, driving her further and further into madness with pleasure. Bellatrix wrenched her orgasm from her body as if it were nothing and in the end the blonde was left weak. The only things keeping her upright were the wall and her elder sister.

Narcissa was allowed to stand at her full height once more with the hand removed from her hair. Those talented fingers that brought her to completion pulled away from her, a muttered charm and they were clean of her fluids.

Her dress tumbled down her exposed flesh when the brunette stepped away. The two just stared each other down for a few minutes, Narcissa's labored breaths floating around them in the hall. Then Bellatrix moved, the small bag from before was in her head and already she was consuming its contents.

"Oh, there you two are!"

The two whipped their heads to the side, seeing their other sister – Andromeda striding down the hall with a frustrated look on her face. "Hello to you as well Andromeda." Bellatrix sneered, brushing past her and presumably returning to their guests.

Once she was gone Andromeda turned her accusing eyes on Narcissa, "Just what the hell were you two up to? You have been gone for ages and Lucius is not happy with your sudden disappearance." she scolded, seizing Narcissa's arm and tugging her further down the hall while continuing to question her.

"Did you and Bella get into some sort of tussle? Your hair is a mess and you look rather out of it…" Narcissa tuned out her sister's worried and suspicious rambling. Her mind replaying what had happened between her and Bellatrix and worrying her lip. It shouldn't have happened and definitely couldn't happen again, right? So then why did her stomach drop and that delicious heat from before stir within her when considering the possibilities of it happening again?

Oh, sister of mine… what am I going to do with you? More importantly, what are you doing to me?