An Avenger's Guardian

Slowly pressing forward, Nebula steered her fingers deep inside, her limb just going deeper and deeper.

"Ahhhh! Ahhhh! Ahhhhhh!" Gamora yelled in agonised pleasure, her face contorting before Natasha's wide eyes.

Nebula felt her elbow slide against her sister's rectum, felt the pulse of Gamora's heartbeat through her fist. Not yet appeased, she slid her arm back till her hand met a ruined green sphincter:

"No! No! Not yet! I-Aahhhhh! AHHHHhhhhhh you bitch..." Gamora moaned flatly as her sister pushed her arm all the way back inside, forearm disappearing a full 15 inches into the shivering green behind.

"Yessssss! Take it, Take it all!" Nebula yelled, her twisting and turning arm making all kinds of slurping, squelching noises as it worked furiously into Gamora's open asshole.

"Ahhhhhhhh!!" Gamora shook in anger, feeling violated and horny as she thrust herself back against Nebula's fist, green flesh rippling as she pounded herself into submission.

Gasping for breath, she flexed in place, back arching to accommodate the deep intrusion into her body. Tightening her grip on the exhausted human, Gamora felt drained and used up, struggling to maintain her posture under the pressure of Nebula's powerful fist.

Seeing the pain in Gamora's eyes, Natasha felt her compassion for the creature return. Gazing down at the green woman's flexing belly and seeing Nebula punching into her from behind, Natasha could only hold the alien as she was gradually over taken by such cruel lust.

Attempting to stop her protector from flailing, Natasha grasped the Gamora with her legs, scissoring the alien as she massaged her sore belly.

Feeling cramps shoot up from her rectum, Gamora realised her body simply couldn't adjust to the arm in her abdomen, even as the redhead cradled her swollen stomach. Realising how deep Nebula had truly gone, the assassin screamed and thrashed in agonised ecstasy.

Running a hand through wavy pink highlights, Natasha tried to calm the broken creature, even as Nebula's cold arm slid deeper still, twisting to keep her sister subdued.

Gamora groaned, her hard voice cracking as she felt Nebula's knuckles in her colon, the entire length of her arm forearm jammed in her asshole.

And then Nebula pulled her arm back yet again and Gamora yelped, jerking uncontrollably as her sister rearranged her bowels, the blue woman pumping relentlessly in and out of her anus, leaving her feral as she began to cum, over and over again.

Running on pure spite, Nebula took deep strokes, taking great joy in violating Thanos' favourite daughter, watching the woman dance like a literal puppet as the warrior manipulated her from the inside. Driving her hand deep with un-tempered ferocity, Gamora laughed manically as she sodomised her sister with her fist.

Clutching her belly, Gamora's green chest bounced with every harsh thrust. No longer holding herself up, the assassin slid forward, falling into Natasha's waiting arms.

Squeezed between the human and her treacherous sister, Gamora felt contorted pleasure even as her bowel twisted painfully; perhaps she had saved Natasha's life instead of taking it. Perhaps that was enough.

Resting her head on the Human's belly, Gamora sank into the waves of oil splashing the twisted sexual partners. Crying out once more, her eyes blurred as she came hard, trapped in the middle of the threesome, losing control of her bodily functions and feeling too much overwhelming pleasure to care.

Not letting up, Nebula worked her strained arm, servos whining at the extreme exertion.

Feeling the heat rise yet again, Gamora whimpered, her voice lost as she spasmed, splashing violently.

Having one last, thunderous orgasm, Nebula couldn't resist one last dig at her sister:

"Behold, Human! Your Guardian at my mercy!"

Her strength finally leaving her, Gamorra felt her mind drift, her jaw slackening and her eyes rolling as unconsciousness took over her frayed nervous system.

Tearing her arm backward, Nebulaa laughed as her wrist burst free of her sister's anus with a loud squelch.

Feeling the pool's oils waft into her anus, Gamora sighed in relief, a tirade of bubbles rising to the surface as she gave in to the cool liquid.

Stroking the back of Gamora's head, Nebula chuckled darkly:

"Ohhh sister; you always were my favourite-"

Natasha watched in dismay as her Guardian slipped, unconscious, between her outstretch thighs, sliding beneath the surface of the pool and out of reach. Disappearing, she left behind a single bubble.

"-Well, now I hate you the least..." Nebula finished smugly.

The bubble burst.

Suddenly concerned for her own wellbeing once more, Natasha scrambled backward, pale and shaking as she met those cold shark eyes.

Falling backward over the pool's rim, Natasha struggled, her belly cramping awkwardly as she crawled away, slipping on the cold wet metal. Dripping and shivering, the soaking redhead could barely move, her ass burning as oil rolled down between her trembling thighs.

"Oh Terran!" Nebula laughed, "Thought I'd forgotten about you??"

Twisting back to face her captor, Natasha watched as the impossibly tall blue woman emerged from the pool gracefully, standing high above her in all her naked, cybernetic glory.

"This was all about her, wasn't it? Natasha croaked, staring up at the warrior alien as she strutted past her.

"They never even consider it do they?" Nebula began, kneeling beside the helpless redhead:

"That beneath the bravado, beyond the body, there lies something submissive, willing to do anything to survive! That's why you are here Terran, just like Gamora! The arrogance that typifies your kind!"

"Humans??" Natasha asked weakly.

"Women!" Nebula replied:

"But I should thank you. Gamora would never have given herself to me. But to some feeble thing like you?"

Eyes narrowing, Nebula smiled darkly, raising the tool she had discarded earlier:

"Now, you will deliver a message for me..."

Natasha watch in horror as the tip of the metal wand lit up. Raised imposingly, the brand burned brightly in the dim light, the curves of an insignia Natasha thought she recognised:

"You know what? I think I'll write it down for you..."

...

Staring down at the marking emblazoned across Natasha's left butt cheek, Maria Hill grimaced, concern barely masked behind her sharp blue eyes. Watching the laser work on the redhead's recuperating asshole, Helen Cho decided to probe the Avenger's Manager for answers:

"None of our decryptors can decipher it-"

Maria shook her head:

"-they don't need to."

Running her thumb over the dark lines of Natasha's new tattoo, the redhead shivered, closed eyelids fluttering. Squeezing her pale cheek, Maria sighed heavily:

"I think they've made their point."