Who are you? I'm the Exile

What if the Doctor wasn't the last Time Lord? This is the story of someone who was banished from Gallifrey. This is the story of the Exile, but who wants to go around being called Exile? So this is the story of Michael, the name that the Exile gave him self this time around, but why has he forgotten who he is, what he is, and why is he banished form his home planet, Gallifrey?