Power

These are hairless apes we're talking about, there's no reason to exert any more energy than necessary.

You weave the borrowed tissue and genetic material from your previous hosts around you into a tight wrap, absorbing information inward toward your core from it. Fortunately, since you're focusing on raw power, you only need to craft a few appendages and biological amenities. You craft the essentials of course. You twine the enzymes into something with enough power to stun the primitives, either to hold them in place or to put them into a deep sleep if you pump out enough. You match chromosomes to something you can use to plug into a nervous system. Not enough to control one yet, but given enough time you come work that. And, of course, you swell up like a balloon. Spending most of your energy on increasing size doesn't do much to give you advantages against predators, but it lets you find a battery and suck energy from them like a sponge.

It's the fastest transformation you've ever achieved... in no small part because of how little you've changed. When you crack your way out of the fleshy egg you formed around yourself, it's not with any new tools or toys. It's because the size of your body splits the shell around you. It's hard to say just how much you've increased in size, but you suspect you won't be able to find another male host. At least not without irreparable damage.

The female host is still writhing in the bed beside you, entwined with her hairy primate lover. Even if she weren't, you would have little use for her anymore. Her most fertile years are behind her, even leaving aside the number of her eggs you personally devoured. You should find a younger female, one with more potential.

The door to the primitive's room presents a problem for you. You developed too much size to utilize the cracks around it and not enough body to utilize the opening mechanism. Fortunately, it seems no small manner of vermin populate this house. There is a hole in the skirting board of the wall that, if squeezed as narrow as is possible, can just barely be fit through. You slide out of the room and into the hollow space between walls. A four-legged rodent peers at you with beady, untrusting eyes. It retreats at your advance, not letting you get close to it.

A wise creature.

You leave it be, sliding downward through support beams and twisting ductwork and out through another hole into the space behind a humming metal box. A quick scan with your feelers detects primitive food cooling techniques, a kitchen of some kind then. You can hear a dull fuzzy artificial noise coming from an attached room, you peak your vision out from the dark crevice.

A young woman is laying down, staring blankly at an electronic box that broadcasts a black and white image. She looks at the images half-interestedly, kicking her legs over the arm of the seat casually. Even half-focused, her eyes are a sharp and interrogative blue. Her shaggy wheat-blonde hair holds the phantom shape of a perpetually pinned-back style but currently hangs into her eyes. That and her simple nightgown tell you she's likely just woken up. Despite a slight hardness to her features, she seems young enough to have just recently reached full adulthood.

Before you can make a move on her, a door opens near her. A young man of similar age walks out in a state of half-dress, pulling the last of his clothing on as he goes. He freezes when the young woman looks at him.

"You can't sleep neither?" He gulps.

"You goin up to the Grisham's again?" She responds dryly.

"You ain't gonna tell ma and pa?"

"If they keep wakin me up like this, I'm gonna go marry Suzy myself just so I can get a quiet bedroom."

The young man nods, completely ignoring her attempts at humor. Judging by the hurry he seems to be in and his age, you suspect he's on his way to go court some bumpkin primate female. He ducks out the door in a hurry and you hear an engine start-up before disappearing into the distance. The young woman sighs and goes back to kicking her legs.

She watches the electronic box until the signal returns only static, soon after you hear the noise in the upper bedroom quiets down. The young woman stands and walks to a different room with a yawn. You almost make it to the door before she steps back out. You dive under a nearby piece of furniture and she pauses like she's seen you. However, she quickly shakes her head and stumbles into the kitchen. She takes enough time for you to wriggle your way under her bed before she returns and closes the door behind her. She noisily throws herself on the rickety bead and you only have to wait a short amount of time before her breathing slows and steadies.

The climb up the railing of her bed is far harder than you expected, leading you to realize you may have underestimated just how big you've gotten. You almost start to wonder if you'll even be able to fit inside your new host. However, you did evolve yourself with some tools to make it happen. You compare yourself against her when on her bed, if you stretch out fully you're just barely longer than her leg from knee to ankle. Not stretched out you're half as long but slightly thicker around than the same section.

You're thankful for her open-bottomed nightgown as you crawl inside. It would be hard to get inside of tight-fitting clothes with any subtlety in your current form and your neurotoxin is best applied internally. You find her pussy, surrounded by a shaggy blonde puff but unmistakable. You stretch yourself thin, giving her entrance a gentle prod and starting to devise the best method for entry. Your gentle, almost feathering prods cause the young woman to stir in her sleep but she doesn't wake up. Her entrance begins to grow slick, both with your natural slimy excretions and her arousal.

You push the first nub of your segmented body through her slit with a gentle but firm thrust. Stretched as thin as you can, it goes in with no real resistance. Your new host whimpers in her sleep. You scrunch your body back up so you can push further in, in the process widening back out and stretching her entrance. She jerks in place but still doesn't wake up. Of course, it was only the most narrow end of you, your fat middle rungs will likely elicit far more dramatic reactions. Once again you stretch thin, this time pushing two segments inside, then contract again.

Her eyes shoot open as she gasps to catch her breath. She mumbles and pulls back the sheets, giving you enough time to push one of your widest segments in before she pulls back her nightdress and sees you. To your surprise, she doesn't scream, her reaction is more of a cold shock.

"This isn't happening, this is a nightmare." You hear her think as your nervous system jacks into hers.

The sensation of one of your widest points spreading her out as you writhe your way inside of her is enough to snap that illusion. She grabs at your body, trying to pull you out but still refusing to scream. Her panicked shaky hands and your naturally slick body make it impossible for her to find purchase. In spite of her silence so far, you decide to play it safe and start to secrete some of your carefully engineered primate sedatives. It starts to take effect almost instantly, you were a chief scientist after all, and her grabbing hands become weaker even if no less . You thin out one more time and slide your thickest segment in, then you widen back out again.

Her scream comes out as a weak squeaking noise, her body starting to feel waterlogged. Her attempts at stopping you become like punches thrown in a dream and eventually she falls backward onto her bed, jaw clenched and eyes looking up at the ceiling. You feel her body shudder and the walls of her sex contracting around you as she experiences an unwilling orgasm. She can only moan and groan, her mouth frothing with each vocalization, as you fill every nanometer of her womb. The constant writhing of your segments against her sensitive insides combines with the near-painful fullness to create sensations unlike anything any creature on earth could make her feel. If the thought that she's the first human being to have sex with an alien crosses her mind, it is quickly wiped out by the constant rubbing and writhing of you inside of her.

Of course, for you, this isn't even sex. Once you've set yourself up fully buried inside of your host, you quietly start working her for everything she can give you. Eggs, body heat, genetic information, even the extra electricity that each of her orgasms provides you with. All of it leads to the constant knitting and weaving of your next, better form. Compared to the first female, this one is an absolute feast. You drive her to orgasm after orgasm, her thoughts getting a little less coherent with each one and the energy feedback getting a little weaker each time. Even the most promising hosts do have their limits.

You can tell this one is starting to reach hers. She falls into periods of sleep, her body attempting to replenish your constant leeching of energy, only to be woken up by another excruciatingly powerful orgasm. All she can do is lie in a puddle of her own fluids. She stopped begging for it to be over after the first few.

So once again, the question of evolution comes up.

With the genetic material you've stolen, you can finally evolve yourself into a "human-like" form. However, there are... limitations to your capabilities. If you make a new form from scratch, you can give yourself the genitals of both a male and female to maximize your spread. However, a created form is more conspicuous. You can only imitate an amalgam of forms you've seen, not create something entirely new.

Alternatively, it would be very easy for you to simply control the current host. You would spread to assimilate her body, either destroying her mind or leaving it intact... somewhere. You would only have one set of genitals, at least unless you built yourself another, which would be extremely limiting. You would blend in better but you would be under greater scrutiny from some and less than others, you would have to choose your next moves far more wisely.