I missed a few parts but the 13th colony, cyclons, left thousands of years ago for Earth. I assume after some conflict because it was alluded to the five knew humanity would make the same mistake again. There was an apocalypse on Earth the five knew was going to happen. They invented resurrection technology and journeyed back to the original twelve colonies. They found the Centurians had rebelled. They offered the Centurians resurrection technology if they would stop the war with the twelve colonies. At that point the centurians had been able to develop hybrids but not the "skinjobs". The five made the human appearance cylons hoping they could feel Love, compassion, creativity and overcome their hate which would lead to peace with the colonies. However, number one (the dean stockwell character)had a sadistic streak and rejected all things human, he rebelled. Here is a quote from his wiki reference..
John Cavil - Wikipedia, the free encyclopedia
In No Exit, it is revealed that Ellen Tigh was involved in the creation of Cavil, modelling him after the image of her own father, John. Cavil was the first of a new generation of Cylons, and he assisted in the creation of models Two to Eight. Because Ellen Tigh favored the Number Seven (Daniel) model, Cavil's jealousy grew and he had the entire line destroyed by tampering with the amniotic fluid that housed the Daniel copies.[3] Cavil was also responsible for the Final Five being banished to live as humans. His rage fueled in part by the Final Five condemning him to an existence complete with all of humanity's weaknesses,[3] and realizing that the Five would try to avert another war against the humans,[3] he killed them and when they resurrected, he erased their memories and left them among the humans so they could witness the eventual genocide of the human race.[4] Cavil manipulated his "parents", the Final Five, to be among those who suffered the most.[5][4] It is also likely (although never explicitly stated) that he was the one who programmed models Two to Eight to not seek out or discuss the Final Five.[4]
After Ellen Tigh was poisoned by her husband, she resurrected aboard one of Cavil's ships and was held prisoner there for 18 months (No Exit). The Cylons' resurrection capability is later destroyed, however, Ellen and the other Final Five retain knowledge of the technology. Cavil decides to kill Ellen and recover the information from her brain, however, Boomer rebels against him and helps Ellen escape.
Cavil fully embraces his identity as a machine and believes that humans are inherently lesser than Cylons,[4]
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