You spotted a trio of units standing on the sidewalk in front of your house, just a bit off to the side. Two of them were standing directly next to each other, while the third was a little ways in front of them. Logic dictated that the two side-by-side units were the parents of the third, the small family enjoying a peaceful walk outside.
But now they stood there, watching you and waiting—possibly for eternity—for your life-changing instructions.
You decided it was time for an experiment.
"Units," you began. "Can I give the three of you a command at the same time?"
The unit closest to you stepped forward. "Master, You are perfectly able to give the three of these units the same command. However, these three will change to be exact replicas of each other in accordance with Your command. While these three are perfectly happy with fulfilling Your requests as stated, this unit believes this outcome will not match Your initial intentions."
"You're right, I don't want you three to become triplets or anything. I was thinking instead I give the three of you a 'prompt' or something, and then you would use your own discretion on how best to fulfill my 'prompt'." The units looked at each other, seeming to have a silent discussion about these revised parameters set upon them by their Master.
"If that is what You wish of these units, they will of course follow Your requests to the best of their ability. Are You certain You wish to give these units the freedom to make such a choice?"
"Well... I mean, would I be able to alter units after you've already transformed? As long as the changes aren't permanent, I think it's okay for you to decide how to alter yourselves in response to my initial prompt." The three units nodded.
"Confirmed. Units will transform to fulfill a Prompt set by Master, but will alter their forms individually within Prompt parameters to maximize diversity between Units. If Master is displeased by a unit's form, He is always able to alter units to better fit His own desires." You smiled. Exactly what you wanted, but put into the words that you couldn't find before.
"Can you give those instructions to every other unit in the world as well? I'd prefer not to have the same conversation twice."
"Master's commands are already felt by every other unit in existence. You must simply say the word, and all units will transform to fit Your desires as Prompted." Your smile turned darker.
"Excellent. With that in mind, I'll start with the three of you just to test things out. You three units are going to become this young boy's family: a father, a mother, and a sibling. All three of you will remain physically male in appearance, but the mother will have a fully working female's reproductive system instead of a male's. For future reference, all units will maintain masculine features no matter the age; the only difference between male and female units is their reproductive system.
"Outside of acting like a normal family would, you will all become hedonistic sluts, willing to perform sex not only with a perfect stranger, but also each other. You will all be perfectly muscled with some healthy fat to balance yourselves out, you will have attractive faces, and high libidos with the sexual stamina to match. You will still have non-sexual interests and hobbies, but you will always be ready for a fuck no matter who it's from."
And with that, their grey flesh began to ripple and quake. You watched as one of the units shifted in height to be somewhere between you and the eight-year-old you just had sex with, while the other two remained about as tall as you. Grey skin turned tanned-pink, hair sprouted from heads and bodies, and sex organs grew from between their legs.
You were a little surprised to see the new sibling also had a functioning pussy, but you figured an even 50-50 split of "male" and "female" made sense.
The two parents turned into absolute DILFs, both with a healthy amount of facial hair (though one had a bit of a salt-and-pepper to his beard). Both had a nice amount of muscle definition and chiseled jaws, but the apparent father (who you mentally named Daddy) had the build of a swimmer while the apparent mother (dubbed Mommy) had more of an off-season powerlifter look to him. Seeing your appreciative gazes, Daddy began stroking his hard cock with a "come hither" look in his eyes and Mommy started stroking his pussy with a look of ecstasy.
The sibling, meanwhile, seemed to be taking after his father in terms of build, though it was nowhere near as defined. A soft dusting of body hair and pubes accentuated his physicality while denoting how he wasn't quite an adult yet. Put quite simply, the boy was a pussy-jock, and quite a horny one too considering his jackrabbiting fingers.
Finally, the changes stopped. A perfectly fuckable family of four, free for use and ready for fun.
With a snap of your fingers, they dove into action.