You can read John McCain's own account of his time as a POW at http://tinyurl.com/ysw3nk . There is a glaring problem with his account.
McCain says that he was treated for his wounds and injuries the first six months of his captivity. He does complain that he was not given immediate medical attention the first four days after he was captured, but this seems unlikely as his wounds were so serious that he would have died if this was true.
Now after this, McCain claims that the Vietnamese wanted to send him back to the U.S. as a goodwill gesture and they became angry when he refused to go. He felt that his going home would demoralize other prisoners. He demanded the release of other prisoners first. The Vietnamese tied him up for one night and beat him for four days according to McCain. He then signed a confession of War Crimes.
The inconsistency consists in his signing a confession of war crimes; while refusing to return home. Why would a severely injured pilot being shipped home demoralize POW's, while signing a confession of War Crimes would not demoralize them? Since the Vietnamese had already sent home other severely injured prisoners as a humanitarian gesture, the other POW's could hardly have felt bad about McCain going back to the United States. On the other hand, having him sign a confession of war crimes, must have severely demoralized them. By not going home, but staying and signing a confession of war crimes McCain, was, in fact, choosing the more demoralizing choice for the POWs. If he was interested in helping his fellow POWs, he would simply have gone home. Even if some may have resented the fact that McCain was sent home before them, they could hardly have ignored the severity of his injuries. It would certainly have cheered them up to know that the Vietnamese really wanted to keep American POWs alive and to send them back to the United States.
But if helping his fellow POWs was not the real reason he voluntarily stayed almost five years in Vietnam more than he had too, what was the real reason? His actions seem to point to the idea that he had a genuine conversion to the Vietnamese side after they saved his life. He voluntarily offered his services to them. This would be my guess for his quite bizarre behavior, the only man in the history of the war who remained a POW out of choice.