Claire/Karen/Natasha:
Karen Page, Claire Temple, and Black Widow stepped into an apartment the size of a closet at the edge of Hell's Kitchen. If Natasha thought that the apartment was small, she didn't comment on it. Her eyes quickly swept the place, out of habit, and Claire offered a tour, which she gladly accepted. The tour never left that room, which functioned as both kitchen and bedroom, but there were several walls to visit, and a desk. Natasha let herself relax, listening to Karen and Claire tell her where every picture in the apartment was taken. Apparently, they'd been able to afford some really nice vacations after Tony Stark started footing the bills at Murdock and Nelson. Besides, as the Avengers' lawyers, Matt and Foggy traveled with them, and Claire and Karen accompanied them, at first as Matt's girlfriend and their secretary, and then as Karen's girlfriend and their secretary. They'd spent a lot of time around the Avengers then, but nothing like this.
"If I'd known this relationship was open," Natasha drawled, "I'd have been in here ages ago."
Karen snorted. "And if we made this public, Tony would be banging our door down, and we'd have to send pieces of him back to Pepper."
Claire added, "It's not a secret, we've done this with Matt and Foggy before. We're just glad our favorite avenger likes us as much as we like her."
"You know, it used to drive me up the wall, trying to figure out how Matt and Foggy suddenly got work representing the Avengers. And Claire couldn't tell me, either. It made a whole lot more sense when Matt introduced me to a ER nurse he dated than when Captain America started bringing us tea so Foggy would finally stop stealing it from next door." Karen grinned. "But I'm certainly glad we met you."
Natasha leaned forward and pecked Karen's lips, and Claire smiled indulgently.
A goofy grin draped on her features, Karen turned to Natasha. "May I take your coat?" she offered.
Natasha, who wasn't wearing one, raised an eyebrow, but made a show of unbuttoning her top, sashaying over to the closet, and hanging it up on a spare hanger. She paged through a few items, intentionally swaying her hips, before she went to bed, where the other two were already waiting for her on either side. She climbed up over Claire, and, straddling her, kissed her full on the lips, parting her own slightly to allow access. Claire eagerly explored her mouth, and ran her fingers at first over Natasha's bra and then unhooked it, once she felt nipples hardening, and caressed newly exposed skin, before turning Natasha over and leaving her on the bed next to Karen, who had been quietly watching their exchange. Natasha felt her lips go dry as Karen ran her fingers lightly down her shoulders and back, and, along with Claire sucked on her breasts until her moans turned nearly to sobs. They all kissed, before Claire returned her attentions to Natasha's breasts, and Karen did her hair up in a ponytail, kissing all the way down her hips and thighs. Natasha swore softly when Karen pressed a brief kiss to her clit, all while Claire's amazing lips were around her nipple and her tongue swirling around. Heeding her cries, Karen dipped her tongue between Natasha's wet folds, and swirled it all around, licking and tasting and nibbling. Claire kissed her other breast, and caressed the newly vacated breast as Karen met Natasha's thrusting hips with kisses and licks. This was Natasha's best night in a long time, even if she was sure their dynamic would continue to change through the future.