Author's Notes: Written for Day One of hp_may_madness with the kink voyeurism, and the additional prompt "Come on… nobody has to know".

Narcissa/Rodolphus and Bellatrix/Rodolphus with a touch of Narcissa/Bellatrix… enjoy!

)O(

Narcissa was appalled when Rodolphus first suggested that she should watch him and Bellatrix.

"Bellatrix would never agree to that," was her first response, and Rodolphus laughed.

"Well, we wouldn't exactly be telling her. I don't expect you to stand out in the open while I fuck her, you silly girl." Rodolphus wrapped his arms tightly around her waist so his body was pressed firmly against hers, clearly hoping to distract her from her shock. "You'd be hiding… only I would know you were there."

"Rodolphus…"

"Come on," Rodolphus urged. He leaned in so his lips were inches from Narcissa's neck. "Nobody has to know – no one but you and I…"

"I wouldn't feel right…" Narcissa squirmed against his too-tight embrace. "She's my sister, Rod."

"So what?" He sounded genuinely like he had no idea why that would upset her. "It isn't as if you'll actually be doing anything with her. Don't tell me that you've never fantasized about her."

Narcissa's cheeks flamed. How did he know? And she had thought that she'd been doing such a good job of hiding her attraction…

"What makes you think that?" she asked haughtily, which made Rodolphus laugh.

"Honestly, Cissa – who wouldn't? I mean, she's such a beautiful girl… just like you…" His hand slid down between her thighs and he ground his palm against her. "Don't pretend that you wouldn't love seeing her beneath me. Just imagine what I could do to her… and you would know that afterwards, I'd go to you, and do all the same things to you…"

Narcissa's knees trembled and she dug her fingers into Rodolphus's shoulders, gasping for breath.

"All right," she whispered at last, her voice thick with want. "All right. I'll do it."

"I knew you would."

)O(

Narcissa hid in the wardrobe in Rodolphus and Bellatrix's bedroom, caught halfway between terror that she would be caught and intense arousal at the idea that she would momentarily be watching her lover and her sister. She had seen erotic pictures, of course, of all varieties, but watching real people in those positions would be an entirely different experience. She was already damp between her thighs.

She heard a moan outside the room and pressed her eye to the crack between the wardrobe doors. The door swung open and Bellatrix and Rodolphus stumbled in, already entangled in each other's arms. Bellatrix's skirt was bunched up, exposing long, fair legs, and she had Rodolphus's shirt open. Narcissa could have cried from want.

"So eager today, Rodolphus," Bellatrix murmured, and Rodolphus grunted in response before shoving Bellatrix off him and onto the bed. He pressed her face-down over it, so her backside was high in the air, and pushed his fingers roughly into her. Narcissa had the perfect view, and she couldn't decide whether she would rather be in Rodolphus's place, fingering Bellatrix, or in Bellatrix's place, being fingered by Rodolphus. Both prospects made her ache.

Bellatrix's face was buried in the pillows, her back arching and bowing as Rodolphus worked his fingers in and out of her, and muffled moans escaping her every few moments. But Rodolphus wasn't looking at her. He was staring at the wardrobe, and though Narcissa knew that she couldn't be seen, she was quite sure that Rodolphus was thinking of her.

She began to touch herself, her fingers working in between her slick folds and her breath coming in low gasps that she suspected would have been audible had Bellatrix not been moaning so loudly. Rodolphus had undone his trousers, and Bellatrix and Narcissa both let out small noises of appreciation when he pulled his cock free and rubbed the tip against Bellatrix.

"Rod, hurry up!" Bellatrix cried, and in her mind, Narcissa echoed her.

She sank to the ground when Rodolphus thrust into Bellatrix, her legs no longer capable of supporting her. Pressing her eye more tightly still to the crack so she could continue to watch, she focussed on pleasuring herself. Her fingers were nowhere near as pleasurable as she knew Rodolphus's cock was, but watching him and Bellatrix more than made up for that. There was no restraint – Bellatrix was moaning and writhing shamelessly, and Rodolphus obviously delighting in it. What a delight it must be for him, to know that he was giving two women so much pleasure, and without even touching one of them.

"Close…" Bellatrix groaned, scrabbling at the bedclothes as Rodolphus and Narcissa both doubled their speeds, Rodolphus gripping Bellatrix's hips while he thrust into her, and Narcissa covering her mouth with one hand to stop from moaning while she fucked herself. She curled her fingers up with every stroke so they hit just the right spot in her, and oh, it was all too much…

Narcissa's back arched and she trembled, biting down on her hand in the effort to keep silent. Pleasure washed over her, sharp and intense, and it left her trembling in its aftermath. She closed her eyes and tilted her head back, and when she had recovered enough that she could see straight and she peered out through the crack again, Bellatrix was collapsed on the bed, Rodolphus on top of her, both of them heaving for breath.

Narcissa felt a moment of disappointment for missing their climactic moment, but then Rodolphus raised his head just slightly and winked mischievously at her.

And nothing could ever be more perfect than that.

)O(

Fin