Okay, this episode was one big info dump. For my own sake I had to break it down. I think this is right.
- The 13th tribe broke away and went to Earth. On Earth they created their own Cylons and went through the whole war thing, destroying each other.
- However, 5 humanoid Cylons ("the final five") managed to get away from Earth and headed back to the 12 colonies.
- The final five were more advanced in that the Cylons on Earth could reproduce. They also had regeneration technology.
- The final five were less advanced in that they didn't have jump drives and it took them forever to get back to the 12 colonies.
- When the 5 returned, they found the centurions going through the same conflict with the Humans that had happened on Earth.
- To get the centurions to stop fighting, the 5 promised them regeneration technology and also created human models (Cavil, Leoben, D'Anna, Six, Boomer). This is why the Cylons suddenly disappeared after the original war.
- The 5 hoped that if they gave these Cylons free will, the ability to love and have human emotions, that the cycle of destruction by the Cylons would end.
- Cavil went a bit nuts, not particularly liking the fact that he was made of meat, and killed the 5.
- When the 5 resurrected, Cavil blocked their memories and then shipped them off to live with the Humans.
- But now that their resurrection ship has been destroyed, Cavil's desperate to get that technology back. Ellen is saying she needs the other of the 5 to do something like that - no idea if it's a lie or the truth.
Oh, and there's some Cylon named Daniel we've never seen. (At least, I don't think we've ever seen a Daniel.)
Also, Mr. PC was the brain surgeon. HA!!
And one more thing, I love Ellen like this! At first I was like, "um, Ellen is the final Cylon?" But seeing her now, it completely fits.