: : This is all in line with the evil nature of Sauron, who often pretends to be well-meaning and a friend, as he did in Numenor, only to corrupt his friends and use them to his advantage.

: : What surprises me is not this, but the fact that he was prepared to respect the life of a hostage at all. Sauron appeared to have practically no respect for life of any sort. Would he have made any attempt to have any of his own people returned had they been captured? I doubt it. Then why would he even begin to believe the captains of the West would be prepared to consider paying such a price for the return of a single, or at the best two hobbits? Yes, I know he was playing, as a cat plays with a trapped mouse before killing it, but it is the fact that he even considered such an offer in his wildest dreams that puzzles me.

: I believe it was because he regarded his enemies as foolish and their weakness lay in their compassion - so he was playing this card thinking them blind to him being so evil that he would have no respect for life.

Sauron was not always evil and therefore had some distant memory of the way the 'balanced' mind works.
He was also using a very base offer (go away and I'll return 1 prisoner) hoping to make the bearer of the one stand forth and challenge him. I am sure he must have concluded that such a small army has no chance, so the wielder of the one must be amongst them here to challenge my power, and hoped to draw them out for a swift strike - the offer of one prisoner an attempt to raise the anger of the 'bearer' into rash action. The point is he missed the double bluff and that gave Frodo (and Gollum) the time they needed.....
IMHO as ever
Dave