He woke up in a white room, tied to a hospital bed and with a few dozen tubes fed into his body. He was confused. He was scared. But none of that compared to the confusion and fear that flooded him when he realized he had new memories. Two sets of new memories. One from the body he was now in...and another set from a fictitious character.
He was confused. He was three people in one body. He was then experimented on. He was in pain.
His name was Jason. He had memories of a time as a soldier in a normal world; our Earth. He had memories of a time as a Marine who served with Frank Castle and memories of the Incident that destroyed most of New York along with the knowledge of the Avengers; memories from the body he was currently in. And finally, he had the memories of a protege of Batman. Jason Todd.
With these memories, and the powers awakened by the experiments, will he be able to escape? Of course. But would he be able to piece himself back together again afterwards?