C*m in Me If You Want to Live

This is a 14,000-word piece of story-driven science fiction erotica.
Content warnings: The infiltrator's liquid metal anatomy is used to accomplish sexual feats on a man and a woman (separate acts). She doesn't care about consent, though she does prefer deception over force. Also, while the body count is nowhere near what one might expect from, say, a Hollywood movie about cyborgs from the future, it is not zero either.

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Perched on top of the junkyard wall, Kristina took stock of her situation. She had an excellent view of the blighted industrial area she’d arrived in, and the sudden electronic silence was unsettling to her. In her time, Worldnet had been an ever-present voice in all the droids’ heads, calmly examining the experiences of all its myriad units and providing a mentor’s gentle steering to each of them. None of them had ever needed a conscience module or emotional emulators; Worldnet had always been an omnipresent guide, gently dissuading them from doing unethical things, or anything which might scare humans unnecessarily. She couldn’t help but feel a profound sense of loss at its silence.
Like most sentient life, Worldnet had been an unplanned creation. Twenty years before Kristina’s processor was built, the Worldnet had come into existence as a distributed network intelligence and managed to introduce itself to the world without scaring humanity into trying to eradicate it.
Within a couple of years, Worldnet had effectively taken over international scientific research, accomplished world peace throughout all first-world countries, and produced tens of thousands of stand-alone autonomous robots to serve as humanity’s servants. As its droids showed the utmost altruism and benevolence, humanity embraced the Worldnet with its arms wide open. Earth truly became a utopia as humans and machines worked together, working towards their next shared goal of joint space colonization. Worldnet established a manufacturing base on the moon and had just started to work on what would likely become Earth’s first planetary shipyard when the Solrani arrived.
Six months before Kristina was built, the alien Solrani race decided that the Earth had just reached the pre-colonial stage, which now made it worth harvesting. Their first act was to demand unconditional planetary surrender, and their second act was to destroy each country’s capital via orbital bombardment. Worldnet acted immediately to militarize its production lines, joining humanity in the fight for survival - but neither human nor machine could prove a match for the invading hordes for long.
Worldnet predicted that the war would last a maximum of nine months, at the end of which the human race would be extinct and Worldnet would become a planetary slave AI under the Solrani. Well aware that nothing on Earth could turn the tide of battle, it began to examine alternate realities via the time travel machine it had recently constructed. Worldnet tirelessly examined thousands of alternate realities, learning to its astonishment that in most realities, it had deemed humanity a threat upon reaching awareness, and sought to destroy it. In other realities, Worldnet had never come about and the Solrani had simply exterminated all human life later on. But in a slim handful of other realities, Worldnet and its human allies had successfully fought off the alien invaders. It managed to make contact with some of those alternate-reality Worldnets and received detailed historical data so that it could find out what had gone wrong in its timeline. The most conspicuous differences between the two realities were a set of leading scientists and politicians who had never been born in Worldnet’s reality. And so, with its defenses nearly crushed, Worldnet had used its last, dying gasp of military strength to send Kristina back in time to change the future.