James Tiptree Jr. Painwise.
Originally in : F&SF
An unsettling story, in which a human, immune to pain, is forced to undergo horrendous acts of atrocity on himself on alien planets to which his ship and AI take him. He finally rebels against this, and forces, painfully, the AI to try and find his home planet. They do finally return to Earth, but he finds out that there is one thing which can cause him pain - Earth itself, and his exile from Earth was doubtless intentional.
22ndNovember 2003
review copyright Mark Watson 2003