A Dragon's Vow (Memory)

Chapter I: The Beginning

We are the Grimleal. Our only purpose is to revive our master, the Lord Grima. Once he walks this land among us, it is our duty to serve him and obey his every command. With Lord Grima's summoning will come a new age.
The great Lord sleeps beneath the mountains, awaiting a vessel strong and pure enough to hold his heart. A vessel of the Divine Dragon's caliber will be hard to find. Hard to acquire.
And yet, it is the Grimleal's sole purpose to do all we can to serve our master. And so, the experimentation began.
The tests started as all tests do: small and simple. Tests were conducted on plants, and rodents. Notes were taken and information was shared, and soon, the subjects of experimentation changed from common rats to reptiles, then small mammals, and finally, humans. Blood was drawn, transfused, spliced, and transfused again, all in an attempt at keeping it alive. Eventually, we were able to consistently make steady transfusions across species, but that was as far as we could get.
At least until we found an old lab hidden under a large mansion. The hidden lab was a treasure trove of information, and using the notes taken by the previous owner, we were finally able to make some headway.
Under the Mountain lies the great Dragon Grima. Priests went under the mountain and drew the master's sacred blood. Using this blood, we were able to fuse it into two children.
Generation I.
Not long after the transfusion, One of the children died. Despite this setback, we were able to carefully raise and cultivate a line of potential vessels. All that was left now, was to await the reveal of the Dragon's brand.
Many generations passed, and the mark never appeared. We wondered if perhaps it was something we had done, and so the priests went to investigate. They were gone for days, which worried many that they had become lost or were killed on their pilgrimage, but the priests returned. However, there was something odd about them.
The priests spoke in an old tongue, that few of us knew. Even those that did know the language could only speak in broken sentences. But we needed only to hear one word.
"Time."
It would take time for the brand to appear, and many years would pass before any of us would be able to see the six eyes of despair upon a human. The vessel must be pure - perfect - and spotless in every way. Such perfection would take time, and the Grimleal had all the time in the world. As long as our master slept. We could continue to serve.
Many generations have passed, so many that we have stopped counting. The number does not matter when the question is "when," and not "what."
Inspections upon the youth have become commonplace. And the bloodline has become to long and scattered to keep track of.
And finally, after hundreds of years, it has appeared.