Frodo in the Tower of Cirith Ungol

[Kuruharan]

Originally Posted by Huinesoron

And finally, he was (once he realised what was happening) in the depths of absolute despair - so far as he knew, the Orcs had the Ring.

That is a good point and points up a flaw in my original thinking. I overlooked Frodo's belief that the orcs had taken the Ring, which would mean that he would no longer have had a mission to try to protect.

Perhaps Frodo struck the orcs as so delusional and strange that there was little to learn from him and that is why they eventually left him alone.