I'm not sure you would call it a do over or not but the MC is a guy/man that was raised with survivalist. One day he is on their property and get hit by lighting and sent back in time to the roman time. He ends up in the body of a prince that was kicked in the head by a horse. I'm sure that at first he shares the body with the boy but something happen where it's just him.
I believe his being there had something to do with the King's wizard