You're bored; leave her there and move on

You had your fun with her and decided you wanted to sample other heroines in the mansion, but you needed a way to get Black Widow out of your hair. You thought for a sec, pretending to be contemplating the next course of action to deal with the intruder.

"Okay, you get back down there to look for more clues while I get Cap and do it naked this time. Don't move until you see me come back with Cap, no matter what."

"On it!" Natasha said as she saluted before she lifted the shirt she put it on and re-assumed her previous position, cum dripping down her bent legs.

"And remember, _do not move._That includes your face so don't even make a sound."

If Natasha had an objection she couldn't voice it. You left the room with her like that and turned off the bathroom light on your way out, blinding her. You left the bathroom door open so anyone who passed by would see her presented backside. As soon as you closed the door to Cap's room you saw the very Captain walking down the hallway to return to his quarters.

"Hey Cap, false alarm," You said as you waved him down to talk, "Me and Widow checked, there's no intruder. You and the team can go back to your usual downtime. Black Widow actually has a surprise for you."

"She does?" Cap responded, placing his shield back on his back once you mentioned the lack of danger.

"Yeah, she does. It's her," Cap looked puzzled at that. "She wants to be your butt **** but she doesn't want anyone else to know, so keep it in the down low. She's embarrassed."

"I see,"

"Yeah, she's laying down in the bathroom for you to use her. Just don't say anything to her when you do. She doesn't want to talk, just sex."

"I don't know about this..."

"Trust me. Don't deny her this. She'll be devastated. Just fuck her whenever you want. In fact, fuck her whenever you think of sex. She's a masturbatory toy for you now. Nothing more. It's what she wants."

"Alright, if it what she wants-"

"It is. Just remember, don't think of her as a person. She's an object, like a bidet or a shower. Now go get her champ!" And with that you clapped Cap on the back for his nice score and walked off.

Black Widow wouldn't leave the stance you left her in until you and Cap were in the same room, and you could make sure that never happened pretty easily. Cap could have his fun and you could have yours. Even if you wanted to double team, as long as she never saw you two at the same time it'd be fine, and with her face glued to the ground that'd never happen by accident. The only issue was her getting fed and hydrated with her mouth closed. That was no longer your problem though. She was Cap's toy now; he'd find a way to give her maintenance. He was a smart cookie. You had other super women to lay. Black Widow was old hat. The doggie style wasn't even that good. It was like she was multitasking while you were fucking.