Lelia begins her story about how it all started, "First thing you need to know is Bloodline abilities..."
Bloodlines, in simple terms, can be called mutated genetic codes. When one awakens a power that is unique and different from all the awakeners who exist in the world, they are called Eons because only one person is born in millennia with that kind of power.
When someone awakens as Eons, they gain a special genetic ability that transfers a part of their unique abilities to their offspring's soul. This way, that unique ability gets transferred from generation to generation, mutating with the passage of time and finally becoming a completely different power.