Automation

You are Flat Spin.
You are walking eagerly behind the cute yellow robot which used to be your friend Gear.
Since becoming a cyborg fucktoy, you've had many chances to enjoy her newly programmed set of skills, but this will be the first time since she was 'upgraded' into a fully mechanical Gearbot.
And while you might miss that wonderful organic pussy, part of you is eager to see what she is capable of now.
Even more exciting, when you told her you were going to fuck her, she seemed to have something prepared.
Which is why you're now following her down stairs and hallways, unable to take your eyes off the sexy robot walking with a calibrated sway of her hips.
Eventually, she opens a door and enters a room with a pony-sized metal table, which she climbs onto.
As you watch, your mouth feeling dry with anticipation, she lies down on her back, spreading her legs and revealing her synthetic bits to you.
A part of you wonders why you had to come all the way over here to do this, but most of your thoughts are on your stiff member and the inviting robot before you.
You climb onto the table and eagerly slide your cock inside the machine. It feels amazing. Not like before, but like it was crafted specifically to bring pleasure to stallions.
Which, of course, it was. It is warm and already wet, and without any need for further conversation, you begin fucking the sexbot.

As soon as you begin, something incredibly happens.
The robot begins to vibrate inside, sending pulses of pleasure up and down your already excited cock.
You gasp in surprise and barely hold it in as you slow your thrusting, allowing the vibrations running along the length of your shaft to send waves of pleasure to your brain.
You feel your cock being coated in something thick and warm, and in spite of yourself, you know you're about to cum.
But you don't.
The feeling builds and builds, past the point of being able to bear, but you still can't climax.
You moan and whimper, desperate for relief, but even though the vibrating feels as good as ever, you still hang on the edge of that wonderful orgasm.
In desperation, you try to pull out, but you only get a few inches out of it before the Gearbot wraps its hindlegs around your rump and pulls your length back inside.
In that moment, though, you saw that the thick liquid wasn't spunk.
It was some kind of liquid latex.
The length of your cock that you managed to see was shiny and artificial looking.
If your whole stallionhood was like that, it would certainly explain why you can't cum.

“S-stop,” you mutter, feebly, “Abort... nnf... cancel...”
But nothing you say has any effect, and part of you doesn't want Gearbot to stop.
The pleasure is no less for your cock being artificial, and the sensations, unabated by climax, make your brain feel like it is melting.
Slowly, the Gearbot reaches a pair of yellow forehooves up, locking them behind your neck, and pulls you in so that your muzzle is pressed against the end of her mechanical one.
You stare into her eyes, and then notice her visor.
Something is going wrong with her visor display.
Bright lights flash on the surface of it. Brief images and words you barely have time to register.
You wonder for a moment if she has a virus or error of some sort.
But as you stare at the visor, you become aware that it isn't an error.
Gearbot is functioning properly.
It is you who has the error.
Gearbot is fixing you.
With your brain battered by the need for an orgasm that will not come, you accept these ideas without resistance.
You think nothing when a transparent yellow visor is lowered in front of your eyes.
When the antennae are attached, you have been expecting it.
The pleasure continues the entire time your organic body is converted to a machine. When at last the mechanical arms finish with you, and most of your body is wonderful metal, a cable snakes from the back of Gearbot's neck like a cobra, creeping around behind you and plugging itself into the back of your mechanical neck.
In that instant, your mind connects with the yellow robot's, and for an instant, you understand.
Then you no longer need to understand.
Your free will is wiped away.
Gearbot overwrites key parts of your personality, leaving you incapable of defying her Mistress. YOUR Mistress, now.
As data flows from her into you, you surrender completely, becoming another drone on the network.
Your fellow drone smiles at you, and you smile back.
Her hindlegs loosen, and you begin mechanically pounding away. Stabilizers deploy from your rear hooves, allowing you to thrust at maximum force, over and over.
What started as a stallion using a sexbot is now just a pair of robots, fucking like the mindless drones that they are.
At last, you are allowed to ejaculate, filling your partner with thick, sticky fluid.
But rather than feeling a sense of exhaustion, you feel only more pleasure.
You do not go limp.
You do not tire.
You are a drone.
As you finish and pull out, you both receive a command from your Mistress. She wants your cock.
The thought gives you more pleasure than at any time during the orgasm denial.
It fills your entire processor as you eagerly move to obey.
Every part of you, mechanical and organic, is programmed to serve Mistress.
You are her fucktoy.
There is no greater pleasure than to please her.
Forever.