They Stole Centuries Worth of Memories

At the age of only 2 weeks, Madison and Isaiah are used as science experiments; lab rats.
Madison and Isaiah are both immortal; kind of. They live, grow old and die like any other human. Then they are reborn into this world but bring all the memories of all their other lives with them. Madison and Isaiah are thought of as dangerous creatures and their creators try to kill them but because they don't die they wipe their memory slate clean and then kill them so that when they are reborn they don't remember a thing. They are then separated to live a normal life but when Madison and Isaiah meet again in 2013 their bond to each other is stronger then ever before and soon they start to remember their memories. Together they grow stronger, they find the powers with in them and the centuries of memories that were stolen from them.