The world was complex and it grew even more when dungeons appeared in the sky like a portal ripping through reality. Then something came out or someone.
It was a human—it looked like a human, they were uncanny to look at but they have the parts of a human body. Perfect in every way, it mimicked flaws as well. It was just one at first but then came another, now there was a woman and a man, both handsome and beautiful.
Everyone thought they just came to see the world but after a year, news spread wide about how those two uncanny people mingled with the humans and the children they bear grew only a week for them to become fully grown.
The news wasn't fast enough to learn that they've been procreating with multiple humans under that one year, creating a large number of "hybrids" on Earth. But the portal was still open, everyone thought their people were going extinct so they came here to make some of their own and that they will leave soon but some didn't think so.
One man went on a rampage, shot down the uncanny "children", the woman and man saw and fled to the portal.
It closed.
But it wasn't long after those portals came back again, appearing in odd times in different hues while the hybrids that survived from the shooting continued to procreate for more children.
And over the last five years, only three families were fully humans.