I have already shared that the crystals came from a meteor that was on a collision course with Earth, and you know that no one seems to know what blew the meteor out of the sky in the first place. This part of the story is likely to never even make it into the book (at least not the first set of stories), but the crystals do have a deeper origin than just "came from outer space."
An alien race called the Yarin, who live on a planet about 18.8 light-years from Earth, have been studying humans for generations. While they have only made one stealthy trip to our system, they did return to their home with several dozen human specimens from around the world. These humans were initially little more than lab rats to the Yarin, but were eventually provided with a secure communal living area so that they could live reasonably normal lives while still remaining as test subjects. None of the original humans remain, but their descendants are still on the planet of Yarix.
The Yarin discovered the essence within the human body—something they do not have. After years of experimentation, they developed a way to focus a body's essence through a device that is black and crystalline. This is not a naturally occurring crystal it's a technology that is crystalline-based. When developing the technology, the Yarin found that even with the crystals, the essence was only able to leave the body while the body was unconscious. This proved troublesome for testing and the Yarin began to induce sleep in order to study the essence further. A second complication arose when the Yarin discovered that each Essence was much more powerful than the human it inhabits: when an essence was free of the body, it displayed abilities that took the Yarin by surprise. They were not ready for what they had let loose on themselves. There were many death—both Yarin and human—and the program was shut down.
Years later, the Yarin Science Consulate discovered that their star, Draconis, was dying. It would still be able to support life in the system for a few thousand years, but there was nothing they could do to save it. H0ping to find a way to revitalize their star, the Yarin turned once again to studying human essence. While none of the humans remaining on Yarix possessed a power that could help, the Yarin were determined to find one that did. They constructed a device that could deliver thousands of crystals to Earth. To lower the chance of their exposure, they constructed the device to look like a meteor. It was designed to shatter shortly before entering the Earth's atmosphere, so that the crystals would be distributed across much of the planet's surface. While they could not control where each landed, they hoped that more would find their way into human hands than not. Along with the crystals, the Yarin sent a Science team to earth, disguised as human, to search for one or more powers that could help save Draconis—and Yarix, along with it.
5 years ago