Author's Notes: Written for Taragh McCarthy's 1st Annual Halloween Competition and literarylesbian37's Femmeslash Challenges.

Warnings: Femmeslash, smut, a little D/S role-playing, sex between people who don't know each other particularly well.

)O(

The Blacks' annual Halloween ball was one of the most popular events in Pureblood society. As such, Narcissa found it boring. She was always relegated to greeting people at the door, and she was always dressed as an angel.

This year was no different. Narcissa stood by the front doors to greet everyone coming in, dressed in her long white robe and wings, bored out of her mind. She could watch the other people dancing – Bellatrix as a devil in a clinging crimson dress, draped all over some man who was turned away from Narcissa, and Andromeda in a hoop-skirt gown with her hair piled high as Marie Antoinette, dancing with Rabastan Lestrange. But she, Narcissa, was relegated to door duty.

The doorbell rung, and she opened the door.

There was a girl standing on the step, looking extremely nervous and clutching a long coat around herself. "Is this… er… is this Sirius Black's house?"

"Yes," Narcissa said, puzzled. "He's my cousin. May I ask your name?"

"It's Lily, Lily Evans," she said. "And er… Sirius invited me over for a Halloween party…?"

"Lily Evans?" The name stirred something in Narcissa's mind. "I know you! We're in the same year at Hogwarts! I'm Narcissa Black."

"Oh yes, I do know you," Lily said, nodding. "And, er… if you wouldn't mind… could I have your opinion on my costume, please? I mean, you know, girl-to-girl."

"Oh… um, of course." Narcissa glanced at the door. They weren't really expecting any more guests that night, as far as she knew, so she led Lily up to the privacy of her bedroom and shut the door. "What is it?"

Lily unbuttoned the coat and let it fall to the floor.

Narcissa choked on her own breath.

Lily was wearing a white blouse, almost half undone. It was so sheer that every detail of the lacy push-up bra she was wearing beneath it was visible. Besides that, she was wearing a grey skirt so tiny it barely covered her backside, and garters and long white stockings. Narcissa gawked. She had never seen someone wearing so little clothing as though it was an ordinary outfit.

Lily tugged nervously on a lock of her red hair. "What do you think? My boyfriend picked it out, do you think it's too revealing?"

A bit of Narcissa's mind wanted to say yes, but she was finding it difficult to speak. Especially when Lily bent over to adjust her garter, which gave Narcissa a good look at her cleavage. Narcissa was no stranger to seeing women in very few clothes – she shared a room with two sisters, after all – but for some reason she found herself completely unable to take her eyes off Lily's body.

"Well, do you?"

Narcissa jolted. Oh, right, Lily had asked her a question. Whether her costume was too revealing.

"Erm… no. No, I think it's… fine." It's fine so long as I can stare at you in it.

"Good." Lily twisted to examine herself in Narcissa's full-length mirror. "Like I said, my boyfriend picked it out, and you know how boys can be…"

Boyfriend.

So Lily had a boyfriend. Of course. One couldn't be as gorgeous as Lily and not have a boyfriend.

Narcissa looked at herself in the mirror as well. Her white robes, the halo enchanted to hover just above her head – she looked the very image of purity. Anyone would look at her and think, What a chaste little creature little Cissy Black is.

If they only knew what she was thinking…

Lily bent over to adjust the strap on her shoe, which caused the hem of her skirt to lift by a few inches, revealing black, lacy underwear. Narcissa couldn't quite suppress a moan of desire.

"Did you say something?" Lily asked. She straightened and turned around before Narcissa could hide the naked desire on her face.

Narcissa's cheeks flushed and she looked down hastily, trying not to think about pulling those lacy knickers off of Lily… and what lay beneath them…

"Narcissa?"

"Yes?" she asked in a tiny voice.

"Were you… were you looking at me?"

"I'm sorry," Narcissa said immediately. "I– I mean, you have a boyfriend… I should go…" She turned around, face flaming, and hurried towards the door.

"Wait."

Narcissa turned back, and her eyes widened. Lily slowly reached for the buttons of her blouse, skilfully flicking each of them undone. She shrugged out of it, letting it fall in a heap on the ground. Now she was wearing only the black lacy bra on her top half. Narcissa's breath caught, and she felt wetness trickle down the insides of her thighs.

"If you want me, then take me. Kiss me, Cissa," Lily breathed, eyes alight with desire. "You're so beautiful…"

Narcissa couldn't stop herself. Her hand flew out to touch the smooth, pale tops of Lily's breasts. Lily let out a moan and massaged her own curvy thighs, rubbing at them through the sheer black stockings and plucking at her garters.

"You said you have a boyfriend…"

"I don't care." One of Lily's hands went up her tiny skirt, lifting it, and she rubbed herself through her black lace knickers, her face registering absolute ecstasy.

There was an incredible ache between Narcissa's thighs now. She fumbled her own skirt up around her hips, and put her hand between her legs, trying desperately to relieve the ache by rubbing as hard as she could.

Lily's eyes glinted. She turned around so her back was to Narcissa, then bent over the bed, her barely-covered ass sticking into the air. She twisted and grinned. "Spank me, Narcissa…"

Narcissa's eyes widened. "What?"

"Spank me," Lily repeated. "In this costume… I want to be spanked…"

Bella's the dominatrix sort, not me! Narcissa thought wildly, but the sight of Lily bent over the bed in those clothes, that tiny little skirt and those garters, made Narcissa forget that. She would try, at least.

She put her hand against Lily's curvy backside, rubbing the smooth, white flesh. "You're a very naughty little girl, you know," she whispered. "Dressed up like a slut." She punctuated the word by slapping Lily's ass.

Lily moaned, and her hands knotted in the blankets. Narcissa felt a rush of satisfaction and slapped her again.

"I'm going to punish you, you naughty little slut," she breathed, feeling her cheeks burn even as she said it, but increasingly surprised to find she was enjoying it. "I'm going to punish you for dressing like that…"

"Yes, ma'am," whispered Lily, writhing on the bed. "I need to be punished…"

"You like being spanked, don't you?" Narcissa asked, giving Lily's ass another two hard smacks. "It's making you so wet…" She trailed her fingers up the damp insides of Lily's thighs.

Lily let out a throaty moan. "Yes… so wet…" She twisted and grinned over her shoulder at Narcissa. "My cunt's dripping for you…"

Narcissa's face flamed. Wetness was running down her own thighs, and she slapped Lily's ass again, watching the soft flesh tremble. "Slutty little girl…"

Lily moaned again, then flipped herself over, spreading her legs wide, pulling her knickers aside. The hair between her legs was as red as that on her head and she was wet and glistening, and Narcissa wanted to touch her and feel her and fuck her.

Lily squirmed in excitement. She grabbed Narcissa and pulled the blonde girl down on top of her. Narcissa's mouth latched on to hers and Lily clutched at the skirt of Narcissa's angel robe, pulling it up around her hips. Her hand went between Narcissa's thighs, and she rubbed her thumb hard over the other girl's clit while slowly easing two fingers into her. Narcissa cried out in pleasure, and Lily slowly began moving her fingers back and forth.

Narcissa bucked against the other girl's hand. Touching herself in the privacy of the night had never given Narcissa anything like this. Lily's fingers were warm and skilful and the perfect size as far as Narcissa was concerned.

"Touch me," Lily told her, using her free hand – the one not buried in Narcissa – to guide Narcissa's hand between her own legs.

Narcissa searched blindly with her fingers until she found the hard nub of flesh that Lily herself was stimulating on Narcissa, and rubbed it, causing Lily's back to arch.

That sight was incredibly erotic to Narcissa. Lily writhing on the bed in only her lacy black undergarments and the skirt bunched around her hips, with Narcissa's hand between her legs.

"Inside me," Lily moaned, head thrashing from side to side. "Inside me, inside me, inside me!"

Narcissa moved her hand a little, then slid two fingers easily inside the other girl. Lily moaned, sweat pouring off her forehead, and Narcissa felt her contract slightly around her fingers.

"Fuck me," Lily whimpered. "Fuck me with your hand, please…"

The words turned Narcissa on more than she would ever have wanted to admit. She did what Lily begged of her, sliding her fingers deep inside, and Lily matched every motion with her own hand. Then Lily's fingers curled up, pressing against the front of Narcissa's passage, and she lost control. Narcissa felt her body tighten, then she was lost, shaking and writhing in pleasure. She dug her fingers into Lily, and, it seemed from a great distance, heard the other girl moan and felt her tighten.

After what seemed like an eternity, Narcissa's body relaxed and she fell forward onto Lily's heaving chest. For a long time, they lay together in silence, then Lily let out a long, shuddering breath.

Narcissa rolled over, so she was lying next to Lily, looking at her. She reached over her for a bowl of candy corn that rested on her bedside table, and popped a kernel into Lily's mouth. Lily let out a delirious little giggle, and imitated the action, slipping a kernel of candy corn into Narcissa's mouth. It was a little, intimate act, a shared bit of almost childish afterplay, and Narcissa smiled widely.

"This," she said, "was the best Halloween ever."

"You know something about Halloween," Lily asked in a gentle murmur.

"What?" asked Narcissa, resting her head on Lily's shoulder.

Lily slipped another piece of candy corn into Narcissa's mouth for her to chew on. "You can be whoever you want to be. It's all in the disguise. People don't have to know who you are the rest of the year, so… it's like being free."

"I don't think I understand what you mean…"

Lily chuckled. "What I mean is that you wouldn't have fucked me if you knew who I was the rest of the year."

"What makes you say that?" Narcissa was taken aback.

Lily smiled, and kissed Narcissa's lips. They tasted of the candy corn.

"Because," she said, "I'm a Mudblood."

)O(

Fin