The Kaleid Blood or Kaleid Bloodline is an artificial bloodline created by the three primogenitor but it was too powerful that they can no longer control it; therefore they divided it to twelve personalities or kaleids that represents the twelve familiars.
The twelve kaleid bloods were given human forms and were in charge of guarding "Root". Somehow, Root devours the 1st, 2nd, 7th, 8th, 9th and 11th Kaleid Bloods while Avrora Florestina persuaded and hunted the 3rd, 4th, 5th, 6th, and 10th. Then she devours Root, completing all the Kaleid Bloods, including herself, the 12th, and becomes the strongest primogenitor, the 4th Primogenitor. Akatsuki Kojou inherited the Kaleid Bloods after consuming Avrora and became the Fourth Primogenitor.