Complex sentence: The character's past, which is alluded to in "Hellbound", is expanded upon in "Hell on Earth" where it is revealed that Pinhead originated as Elliott Spenser, a captain in the British Expeditionary Force suffering from PTSD and survivor guilt.
Split into simpler sentences: The character's past, which is alluded to in "Hellbound", is expanded upon in "Hell on Earth". It is revealed that Pinhead originated as Elliott Spenser, a captain in the British Expeditionary Force suffering from PTSD and survivor guilt.