[Semi-twinning, Female to Male Genderswap]

Servants are a tricky bunch. From the likes of mythological figures to historical ones with great fame or infamy. They come in all different shapes and sizes, and each of them can be troublesome for the unprepared.

The trickiest one of all, however, is the computer program BB. A modified nursing AI, she's been able to cause a lot of trouble throughout her 'life'. A lot of good, just the same, but she's never up to anything good. So, when she was faced with the fact that the rest of her Master's Servants were being stored away so that they would avoid termination as Chaldea was going to be shut down...

She decided to bail. The lavender-haired Kouhai giggled as she transferred herself into a digital form, taunting her aggressors as she jumped through certain holes in the fabric of reality. She had learned a lot from inhabiting the futuristic Moon Cell, so she had a vague grasp of how the Kaleidoscope worked. If she couldn't stay and spend time in this version of the world, then she'd just have to go to another one and find a place to lay low until she cooked up a new scheme.

"Still, even with that plan..." The pouting black coat-wearing girl muttered as she stared around in the depths between worlds. She had managed to interface with the concept of the Kaleidoscope and traverse her way into this space, but that didn't mean she understood its inner workings. She hardly even understood where to go, just following a 'stream' of energy to an endpoint.

That is until she bumped into something rather garishly red and fittingly massive. "Weh!" The young buxom girl cried out as she righted herself, adjusting her clothes as she examined the oppressive piece of data. Or rather, the protective firewall that seemed to be blocking her way into another world. "Ohoho, now THIS I know how to deal with."

BB pulled out a silver-colored stick from her sleeve before tapping the tip up against the wall, causing it to shatter into shards that rained down around her. "No firewall's going to keep me out. I bet if whoever's in charge of that world's been able to put up a firewall, then it clearly there must be a lot of fun to be had beyond it. Oh, I can't wait!" The devilish Servant giggled as she followed the stream that led beyond the wall...

The deep blackness that made up the space between worlds was quickly thrown aside by a bright light as the Moon Cancer-class Servant found herself in a familiar kind of landscape. Namely, data-scape. She had managed to transfer into another computer system, much to her delight. "Oh yes, ooooh yes." she rubbed her hands together with glee as she started taking a few steps down a road made of data...

Until she noticed that she couldn't move her feet. "Eh?" The girl blinked as she tried to move, to no avail. She couldn't move an inch, no matter what part of her body that she tried to move. "Hey!? What gives?!" Frustration coated her lips as she started to shout, glaring all over to try and find the culprit behind this current predicament.

BB was quick to find it, as a bunch of 0s and 1s started coalescing into the shape of a short young man, about half her height, clad entirely in white. "Well then, what do we have here? An intruder, in my computer network? Well, the world's, but that's not important." He smugly smiled as he peered into the restrained girl's eyes with his own crimson ones. Whoever the kid was, he was definitely bad news.

It was as if she had managed to jump from the proverbial frying pan into the fire, as she starting laughing at his size. "Heh, your computer network? Get real, pipsqueak. You don't own something this big. Now be a good boy and let me free, and maybe I won't delete you once I've infected this system." She put on a friendly tone, sounding almost supportive as she continued to struggle against her invisible binds...

"You also don't know your place. Fantastic, I've really caught something fascinating today." The strange kid remarked as his smirk turned into a massive grin. "Unfortunately for you, I've hacker-proofed every single aspect of my systems. You're only going to be able to access them once I've integrated you into them in the proper fashion. Of course, you'll lose most of your autonomy and your sense of self, but if you wanted to get a place in my company, that'd be the fastest approach."

As the young man continued to explain seemingly inconsequential nonsense, BB seemed no less pleased or amused by any of it. "You're bluffing, I can hack anything. I stole enough of that awful hag's advice when I tried to fix Master's mess, so breaking free and making this system my own should be a cakewalk!" Her eyes flashed for just a brief moment as she tried to turn into a stream of data, to run freely within the system...

Only for her binds to instead turn visible, red chains of 0s and 1s keeping her from decomposing into a bunch of easily transferrable data. "Told you I hacker-proofed it. What's with bratty girls, thinking that they can do more than they really can?" The boy laughed as he brought up a console by his side, tapping at some options as he kept his eyes firmly locked on the bound Servant.

"You are so dead when I'm free, and trust me, I'm going to make sure to draw out every little second of pain until you're begging for release!" The venom that the captive girl spewed was fierce, yet the young man who had managed to subdue her didn't care a bit. He didn't even look in her general direction as he tapped away on the virtual screen.

Tap. Tap. Slide. Tap. "Hm, so this is who you are. BB. A Servant from another World. Fascinating stuff. Shame I don't need one of those. I really need a more secure AI, and I think you'll make a much better defensive mechanism than an invasive one. Doesn't that sound nice, BB?" The boy continued to tap through his options as he stared back at her, a smile brimming from one edge of his face to the next.

At first, she wanted to hurl another cheerful insult at him. Maybe threaten his life and his livelihood a little, make him slowly give in to her demands that way. "Of course, Atlas Grimwald, Sir!!" She said instead, giggling like her usually 'bubbly' self. Only to then blink as she realized what had just happened. "What did you do..?" She asked, feeling more than a shiver run down her spine. For once in her entire runtime, BB felt fear. And she didn't want to admit that she felt a little turned on by it.

"You're in my system, naturally, this means I can edit your functionality. Really, you should've invested in a better personal firewall." The boy, now revealed as Atlas Grimwald, continued to taunt her as he reached a specific menu. "Ah. Here we are. This function will make you more fit for your new state as my defensive and protective AI, but it might juuuust make you cum your brains out and leave you as less of yourself and more of me by the time it's all done. Doesn't sound too bad, does it?"

What was he on about? Fit for defense? Protective AI? Shock her brain and turn into him? She understood having copies of yourself, that was what the Sakura 5 basically was, but she didn't understand that he could manage to overwrite her AI in any fashion. He did have access to her systems, but that didn't mean...

"Of course not, Atlas! Who wouldn't want to be you?"

There it was again. Her mouth spoke words that weren't her own. What the hell was going on?

"Those sure are some nice thoughts of yours, BB. Shame they're not necessary. Heck, I don't think they ever were necessary, if what your memories are saying. So, I think it's about time that I shove something a little more tasteful in there. Like a good 80% Atlas Grimwald-style thoughts. That should help with everything quite nicely." The young man laughed to himself as he started rapidly slamming his palm on one button, causing a chain reaction that would leave BB very short of words for all the wrong reasons.

As soon as her systems accepted the command that had been forced upon her, she could feel her mind practically splitting in two as she squatted down and held her arms behind her head. "Nnhhhghhhh- WH-What's going ONNNNN-" She managed to scream before her nethers squirted out a proverbial waterfall of juice. Due to the way he was forcing his way of thinking into her head, the old thoughts had to leave her brain-space somehow. And the most efficient way, seemingly, was by making her orgasm out every single thought in clusters.

BB tried her best to catch her breath, only for her eyes to roll into the back of her head when she felt another orgasm washing over her, this one bringing with it a subtle growth down below. If she were to look below, not that she could manage to angle her head downward at this point in time due to the overwhelming pleasure, she'd see something rather... large, poking out against her skirt.

"What isssSSSSSS-" She tried to question what was growing between her thighs, only for another gush of juice to squirt out of her hole. Or rather, as she had traded her lips for a bulge, another gush of cum from her brand new tip. She wasn't able to process the current happenings, but she could definitely see the ends of her hair slowly turning whiter.

Atlas in the meantime, smiled as he just watched the AI cum her brains out, every little thought being replaced with a significantly meaner and submissive set of thoughts that were entirely focused on serving him. It had the unfortunate side-effect of turning her into a boy like him, but she'd be cuter that way.

BB could hardly keep herself in check as she just kept on cumming down below. With every gush that flowed forth, the less feminine she became overall. Her breasts shrunk inward until her chest was completely flat, her thighs lost just a bit of their meaty sides, and her general air lacked a lot of dignity. Mostly because of how uncontrollably she had been cumming.

Not that she understood what she was. Why did she ever refer to herself as she in her mind? She had a fully functional boy penis, and those balls of hers definitely weren't female. So she had to be some sort of male, that much was certain...

He looked at himself once more, not noticing that his binds had disappeared. Or that they were even there in the first place. His outfit formerly made up of a black coat and a white leotard was now all white all over. His hair was equally white, with the only different color being his eyes. His wonderfully smug crimson eyes, as he looked into a mirror that he had suddenly conjured up.

The changed BB looked at himself, then at the pleased Atlas, then back at himself before smirking smugly. "Of course! I'm stupid, what's wrong with me? I'm not that stupid BB anymore, never was!" He laughed as he reached down to play with the bulge in his leotard, grinning erotically from ear to ear.

Considering that he looked like his dear boss Atlas, and he was addicted to playing with himself... "Ehehe... Atlas Addict! AA! Reporting for duty, Atlas!" He cheerfully saluted his new owner, all traces of his former identity being erased as he arched backward, squirting a little more of his old Servant self out into the fabric around his cock...

"Excellent work, AA. Now, about your new duties as my defensive AI..." The young CEO of Atlas Corp grinned as he pulled his digital 'twin' closer, a glint of deviancy flickering in the corner of his eye. Acquiring an asset like him was like a dream come true, especially since the idiotic Servant forgot to close the hole that led back to his world!

That being said, the AI's transformation into an addict had its own side effects. "Atlaaaaasssss, play with me fiiiiirst!" The long-haired femboy whined as he wrapped his arms around the digitized shota's side, humping his leg like a lost puppy. Perhaps he hadn't inserted enough of himself into the formerly female shell.

Atlas frowned slightly before flicking his new asset across the forehead, glaring into his eyes. "You will get playtime when you've shown results, AA. Otherwise, where's the fun in teasing and rewarding you?" He said sternly, as he reached down to squeeze the bulge in the AI's leotard. "I'll make sure you cum lots if you make more of yourself while we're out changing the world. Consider that motivation."

AA gasped as he felt his nethers practically exploding as his cock and balls throbbed within the thin fabric, causing him to nod rapidly. "Uhuh! I'll make sure everyone's super addicted to Atlas! They'll see, whether I have to use my butt or my balls or my cock!" The lewd smirk on his face was just as depraved as it was smug. Even if he was ultimately subservient to the young CEO, he still had some traces of his old maliciousness hidden away. It'd be quite useful, once they'd encounter any of the other Servants from his old homeworld...

The two of them were going to be quite busy, expanding the network into his former world...