The Adams and Eves were the original eight million colonists sent to Safehold as part of Operation Ark.
As a reference to the ancient Jewish story of the origin of man, Eric Langhorne's team named these colonists "adams" and "eves" after changing their memories so that they believed to have been created by a God.
Due to their genetic and nanotechnical enhancements, the Adams and Eves had a considerably longer lifespan then their own offspring; many of them lived to see their grandchildren and great-grandchildren grow, a fact they attributed to their "direct" creation by God. (OAR)
During the War Against the Fallen, Maruyama Chihiro and his followers partially restored the memories of certain Adams and Eves, including Cody Cortazar, and used them as agents to restore order and smoke out the remaining supporters of the "Fallen". (HFQ)