That cause is revealed when Crichton is kidnapped by Scarrans – during his torture on the base, Scorpius had implanted Crichton with a neural chip that contains a clone of his personality, designed to track down the wormhole knowledge and protect Crichton and Scorpius both until that knowledge is found. Crichton nicknames the clone Harvey and it begins to manifest as hallucinations to him.
that cause is revealed when crichton is kidnapped by scarrans – during his torture on the base scorpius had implanted crichton with a neural chip that contains a clone of his personality designed to track down the wormhole knowledge and protect crichton and scorpius both until that knowledge is found crichton nicknames the clone harvey and it begins to manifest as hallucinations to him