Survival is a major theme. Characters in these books often have to fight for their lives in the harsh conditions of the penal colony. For example, in 'Papillon', the main character constantly battles against the elements and the guards to stay alive.
Redemption is another common theme. Some characters may seek to atone for their past sins while in the penal colony. In 'For the Term of His Natural Life', the protagonist's journey is also about finding some form of redemption in the face of his long - term imprisonment.