You try to

You approach her and as gently as you can, slide your hard dick into her asshole. Even at this she winces a little. "Are you ok?" You ask.
"Yeah, fine."She replies without turning round. You move in and out slowly a few times, trying not to hurt your ally too much. Nut the crowd aren't interested.
"HARDER! HARDER! HARDER!" The crowd chants. You try to ignore them but it isn't long before the announcer reminds you of whats at stake.
"You better give the crowd what they want!" He bellows. Black Widow looks over her shoulder at you stone faced.
"Do it." She tells you. You thrust in a little harder and she bites her lip and turns back around. The crowd goes wild as you thrust in and out with more power. You'd never admit it to her but the muffled moans of Black Widow turn you on and encourage you to keep going. You feel yourself ready to cum and assuming its what the crowd want you bury your cock deep in Natasha's ass, shooting off a huge load as deep as you can. The crowd goes wild. You remove your dick from her and stand up. She remains where she is as a blue beam surrounds you and transports you to a holding pen with the rest of the Avengers. They gasp at seeing you with your dick out and a naked Black Widow with cum dripping out her ass.