Fun fact I didn't know before: the Phoenix Force is sort of Thor's mother in the comics.

They’d only half explained the mission to Thor before he was already disrobing. He seemed unfazed at the though of breeding with his teammate, though considering his mythical reputation for bedding mortals this was perhaps unsurprising. They hadn’t even mentioned the hope the entity would leave Natasha once it had fulfilled its function and she had conceived.

“And you’re sure Banner does not object?” Thor asked amiably, unbuckling his chestplate to expose his rippling torso.

“He’s… having nap time,” Stark said. The Avengers who had seen what was left of the Hulk exchanged glances, neglecting to mention to Thor what the entity had done to the ex-man. It might only give him performance anxiety.

Thor removed his pants. Stark, shielding his eyes as best as he could from the emasculating, godly

penis, crouched and affixed the Stark-tech codpiece to the top of Thor’s member. It gripped the thick shaft, unfurling a series of titanium-gold armor plates that ensheathed Thor’s dick, leaving just the tip exposed.

“She’s got an internal temperature to match the surface of the sun, so don’t hang around. This armor is only rated to hold up for a few minutes,” Stark said.

“If that’s the case we should send you, sir,” Jarvis interjected dryly.

“Just shoot your shot and get out of there,” Clint said.

“We’re with you every step of the way,” said Steve. “You know we’d all be in your place if we could.”

“Come now, this is hardly my first goddess. Your concern is misplaced,” Thor scoffed. “Did I ever tell of the time I bedded the queen of the Frost Giants? The frostbite was-"

"Only a thousand times," Stark muttered. "Alright, you're armored up. Go get her, tiger."

After what had become of the Hulk, they’d sealed Natasha in the same glass cell that Loki had once occupied. It was of her own volition - they suspected there was little capable of containing the entity inside her if it truly wanted to get out.

Natasha regarded her teammate impassively as he strode naked into the room, heavy and heavily-armored dick waggling. Thor and her were friends, nothing, but he'd be far from the first man she'd slept with out of service to the mission. She sighed and spread her legs, reaching for the well-oiled catsuit zipper.

The being within her flared. "Not that one."

"What?!" she gasped. "Why not?!”

“I was there, with Odin, when this one was conceived. This one is like my… child.”

Natasha groaned. “You've been telling me to breed with everything else on this ship, and now you say no?!"

“You may have any other but This. One. Is. Mine.”

Thor’s swagger lost its cocksuredness. As dark fire began to whip about his would-be-conquest, thoughts of sex vanished. She rose into the air, and he felt tiny before her. Only one person in the nine realms could ever make him feel so small - his mother, Frigga.

Her flames spilled from the cell, and licked up his legs. His musculature burned away, exposing new, smooth skin beneath, slender calves and feminine thighs. The armored cocksheath clattered to the floor as his manhood dwindled, incinerating in wisps of ash sucked away by the automatic fire suppressions.

"What are you?" he gasped. Top heavy, a bulky bodybuilder's upper body perched upon fashion model legs, he toppled backwards onto his full ass, sprawling in the fire that ate hungrily at him. She glided above her, staring down with maternal pride as his body warped.

"Many worlds called me the Phoenix. But you may call me mommy."