Within my main story arc, the antagonist replaces parts of himself with machinery, in order to live forever (for more information on this refer to my "Complicity or Simplicity of the plot" thread), but since the story arc starts in medieval times and goes through 600 years to the 1800's, but the way he replaces his body parts is one by one, yet he replaces his innards and his outward body, how could this happen? The technology wouldn't exist. I want to stick wiht some kind of science, but, while a few parts of this rely on improbability and such, I want some of it to follow some science. Any help would be great, Plus I don't know if this belongs in this part of the forums or in character development, so forgive me there. Thanks in advance for any help.