The_Dreamwalker
The T8-00 was created not long before the Sole Survivor was released from cryo hibernation. He was designed as a Prototype Generation 3.5 model. He looked and performed like a Generation 3 Courser, but had the interior skeleton of a Generation 2 Synth, but was built to be far stronger. The T8-00 was built for the sole purpose of open war, as it could do what an entire army of Synths could not.
After a run in with Glory, an operator in the Railroad, the T8-00 suffers head damage which makes him remember former memories. These memories confuse him and he wishes to discover what they mean. Since the Institute refuses to help and claims he needs fixing, he refuses to be their puppet anymore and escapes into the Commonwealth. There he will encounter more enemies and some allies, and maybe he will make sense of his memories, too.