Author's Notes: Written for Lady Phoenix Fire Rose's Pairing One Hour Challenge/Hardest Challenge Ever with the triad Andromeda/Narcissa/Walburga and the prompt "My word".
Also for Weekly Quick Fic #3 on writerverse on LiveJournal with the prompt "It's only the end of the world".
Warnings: Sister/sister and implied aunt/niece/niece incest.
Narcissa and Andromeda were entangled on Andromeda's bed, kissing each other feverishly. When they had begun, they had been careful to be quiet for fear of being heard by their Aunt Walburga, who had been given the task of watching over them that afternoon, but as time had passed and their kissing had become more passionate, that carefulness had been forgotten. Now Narcissa was panting breathlessly, trembling and clinging to her sister as her fingers worked inside her. She was covered in a pretty sheen of sweat, her usually pale cheeks flushed pink, and a string of quiet, sweet little moans issued from her lips.
"I love you so much, Cissy…" Andromeda kissed her neck lightly and she responded with a sigh of pleasure.
"I love you too… oh Andi!" Her voice was higher than normal, tremulous and breathless and Andromeda pressed her mouth down over hers, silencing her.
"Don't… want to be heard…" Andromeda murmured. The vibrations of her voice against Narcissa's lips felt so terribly good and Narcissa flung her arms tightly around her sister, rocking her hips against her hand.
Andromeda flew away from Narcissa immediately at the sound of their aunt's voice. Narcissa's eyes had fluttered shut and they opened immediately, and she squealed, grabbing at the bed sheets and trying to cover herself.
Walburga was standing in the doorway, her usually sallow face positively white and her hand up as though she had just turned the knob. Andromeda was already scrambling for her clothes, trying to grab at them while covering her exposed breasts, and Narcissa had frozen completely still, staring at her aunt with absolute terror written all over her face.
"Aunt Walburga, we weren't–" Andromeda began, but there wasn't any point. There was absolutely no ambiguity about what they had been doing – only one explanation existed for why two young women would be lying in bed bed, both completely undressed and one with her fingers buried inside another.
"Don't bother lying," Walburga said, and though her face was still as white as the sheets upon which Narcissa and Andromeda were huddled, her voice was quite calm. "There really isn't any point and you'll only make fool of yourselves."
"Are you going to tell Mother and Father?" Narcissa peeped. Andromeda clapped a hand over her mouth, as though that would stop the words from coming out.
"Absolutely not," said Walburga, even more calmly – almost coldly, almost clinically. "That would reflect most poorly on me as a guardian, wouldn't you say?"
"You're- you're acting as though this is unimportant." Andromeda sounded both perplexed and suspicious and she was eyeing her aunt as though she was about to be told that there was some catch and that their secret was not really safe. That it was seemed too good to be true.
"It is rather unimportant."
"Unimportant?" Narcissa pried her sister's hand from her mouth so that she could speak. "How can you say that it is unimportant! It's- it's only the end of the world–"
"Narcissa, that's stupid!" Andromeda muttered, but Narcissa didn't care.
"What are you not telling us yet?" she demanded of her aunt. "What do you want in return for silence? No one would not take a situation like this as an opportunity for blackmail–"
"Narcissa, shut up!" hissed Andromeda. "You're going to give her ideas!" But there was already a small smile upon Walburga's lips and she considered Narcissa with something akin to pride.
"You are so very much a Slytherin," she said, and Narcissa thought it extremely strange that she was being commended on her Slytherin behaviour by her aunt while she was undressed, sweaty and damp. This was not a usual situation for being commended on anything…
"There was something that I wanted," Walburga continued, and Narcissa and Andromeda exchanged glances. Andromeda looked angry, as though she thought that it was Narcissa's fault, and Narcissa looked triumphant, for she had known that her aunt would not willingly give her silence.
"What do you want, then?" Andromeda asked at last, unwillingly, looking up at Walburga.
Walburga did not answer immediately. She looked both girls up and down with such intensity that Narcissa's cheeks went crimson. She had never felt so exposed before, not when her sister had first taken off her clothes, not when they had been at school and had made love against the wall in a corridor while expecting to be caught at any moment, not ever. Narcissa was modest by nature and could only be persuaded to display herself when she was in the heat of passion, which she most certainly was not anymore.
"Stand up, Narcissa," Walburga said at last, and Narcissa looked worriedly at her sister before she complied, standing slowly and holding her hands in front of herself to shield the small patch of fair hair between her legs from her aunt's view. She had to leave her breasts visible, but that was hardly as humiliating as trying – and failing – to cover them both would have been.
"Put your hands down," Walburga said firmly and Narcissa dropped her hands to her sides immediately, not daring to refuse. Her face must have been positively scarlet all over and she desperately wanted the floor to open up and swallow her, but she stood still and steady in front of her aunt until Walburga's hand moved out and rested on Narcissa's left breast, right above her heart.
She jolted back. "What are you–"
"I don't think that it would be an at all unreasonable price for my silence," Walburga murmured, "if you two were to allow me to join you."
She kissed Narcissa before she even had a chance to protest, and she wouldn't have dared to even if she had had the chance.
Better, she thought, as her aunt pushed her back down onto the bed, to be in this situation, however humiliating it was, than to have her parents know what she and her sister did to each other.