Many years ago, a rogue faction of the Kree came to the Earth. Their intentions were to use us humans as experiments -- to create genetically altered soldiers and tinker with our bloodlines. Many believe that was so they could plunge the Earth into chaos and war, but that isn't necessarily true. What this group hoped to accomplish was to build an earth for the worthy. They left behind cities and alien technology to allow us humans with Kree blood to awaken our truer selves. This same technology could destroy those it didn't deem worthy. I've seen it happen first hand. A man exposed to terrigen crystals turned to stone and crumbled into nothing right before my very eyes.