This story is part 18 of the 'An Avenger's...' series but can be enjoyed as a standalone.
These events take place in a Post-Snap world featuring characters from across the MCU.
...
"Ridiculous!!"
Dark sultry voice wavering, Nebula still managed to scoff at the ridiculous human; even as her cybernetic body was overwhelmed with pleasure.
Perched on the rim of the huge circular machine the alien woman shuddered, toned muscles and machinery flexing through her tight purple suit; blue behind polishing the shining metal surface as she reluctantly accepted oral stimulation from this voracious ape descendant.
When Nebula had arrived on Earth five years ago she had expected little of its backward human inhabitants. Upon meeting the Avengers however she had been surprised to find one that she had known before; very intimately. Joining Earth's 'mightiest' heroes Nebula had been curious to understand how the Black Widow could possibly contribute, given her human weakness and lack of super abilities. But she certainly had her uses:
For Natasha Romanoff this was an all too familiar position; staring lustily up at a woman from between her thighs whilst lapping at her open flower. Of course, Nebula wasn't technically a woman, and her thighs were blue... But most importantly Natasha wasn't doing this on someone else's whim; for once the Black Widow was seducing on her own terms. With most people all the redhead had to do was bat her eyelashes and smile provocatively to gain their favour. But in these hard times she often had to exert a little more effort...
Tasting exotic juices on her tongue, Natasha revelled in the sublime heat of her former- abductor's delicious pussy, sucking on Nebula's swollen purple fruit with a new sense of purpose; hopeful for the first time in years now that the Avengers had a plan to save the universe.
Taking several long deep licks Natasha twirled inside the alien woman, running her tongue over the velvety inner walls before flicking at Nebula's g-spot. Finally peeling her mouth away from Nebula's pussy Natasha grinned up at the aggressive cyborg, juices dripping down her chin:
"Why is it ridiculous? I'm doing something for you... Why can't you do this for me??"
Growling under her breath Nebula grasped the back of Natasha's head, strong metal fingers tugging on the Avenger's loose red braid. Shoving the impudent woman back between her thighs, Nebula rode her face roughly as she replied:
"Why!?! Ungh! We built this machine to undo the Snap -- Nnnngh! To use the Quantum realm to undo the horrors my father inflicted across the universe -Unnghh! Tomorrow we will carry out the..." Nebula shook her head in disdain at Scott Lang's ridiculous terminology:
"... Timeheist. Ughhh! -but tonight you want to take it on a joyride?!"
Smothered in alien pussy Natasha could hardly reply; redhead trapped between those strong blue thighs. Electing to use her own skills to soothe the raging warrior, Natasha ran her tongue between the folds before her:
Cheeks hollowing as she blew into the alien's core, Nebula clutched her face tightly as the alien woman bucked against the time machine:
"Unnnghhhh!!!"
Seconds later Nebula squirted into Natasha's open mouth, her cream spraying the back of the redhead's throat:
Swallowing the cyborg's cum was not an experience Natasha could ever get used to: Unlike a human woman's juices Nebula's came out incredibly hot, burning the back of Natasha's throat as she gulped down the spicy liquid. Smiling into the blue pussy however, Natasha swallowed several more mouthfuls of Nebula's hot sauce; determined to ease this creature into returning a very big favour.
Nebula flexed against the giant glass disc of the time machine, servos whining as the redhead gave her a mind-blowing climax. Feeling her pussy explode the alien flushed slightly, feeling some pity for the woman beneath her; Luphomoid juices were a highly potent diarrhetic.
Holding on Natasha swallowed, struggling to contain Nebula's hot excretions. Still perched on her knees Natasha pulled away as the cyborg released her, the Avenger gasping for breath.
Wiping at her swollen lips Natasha fanned her tongue, replying in her distinctive sultry voice:
"More like a time... tryst. You know I have a dark past, red in my ledger?"
Nodding, Nebula watched as the naked redhead rose up from between her legs: "I'd like to wipe it out."
"But any unnecessary temporal manipulations can create branches in time!" Nebula growled indignantly:
"Unstable dimensional openings, spatial paradoxes, time loops! You want to get stuck reliving the same moment over and over?"
Pressing against her opponent Natasha whispered into Nebula's ear:
"Depends on the moment... Besides, that's why I need your help. And you know how persuasive I can be..."
Tickling her swollen labia Nebula swatted the insatiable redhead away, crossing her arms stubbornly as she summoned up true resistance:
"No."
Natasha's face fell, revealing the hard determination behind her eyes to the reformed alien woman: the Black Widow was on a mission to return to her past and nobody would get in her way.
Sensing strength she had never seen in the redhead, Nebula was shocked by this sudden transformation. Natasha simply twisted on the spot, gesticulating to her hip. Gaze rolling downward over those pale curves to the redhead's bloated behind, Nebula's spotted the star symbol she had once tattooed there; the oppressive symbol of the mad-titan Thanos:
"You owe me." Natasha murmured.
Considering the redhead's insane request once more Nebula ground her teeth:
"It won't matter! We only have enough Pym particles for the Timeheist and that's it! No do overs."
Natasha smiled slyly: "Don't we?"
Reaching behind her, Nebula's eyes widened in amazement as the redhead revealed several red test tubes:
"Where did you get those?!"
"I infiltrated Pym Tech years ago. Hope and I have... had a give and take relationship."
Leant up against the alien cyborg, Nebula couldn't help but enjoy how Natasha's pendulous breasts pressed against her own; blue and pink nipples brushing delightfully as the two negotiated:
"But they would never just let you take Pym particles?"
"Well no, I had to smuggle them out up my..."
Biting her tongue Natasha blushed ever-so-slightly, suddenly unable to meet those dark shark eyes: