When I first saw this theory, I found it very intriguing so I decided to pursue it.

It wouldn't be very difficult for Demandred to pull this off. They're both good generals, he and Osan'gar were supposed to keep an eye on Rand.

It would give him easy access to Taim and the Asha'man.

Also, this gives us another explanation of why Bashere doesn't recognize Taim: he's not really Bashere.

It would be very subtle of Jordan to put that in there. Especially considering Bashere also has Demandred's features. (hawk nose, almost handsome etc.)

The one problem that Tamyrlin pointed out in this theory is that he wouldn't be able to fool Deira. But then again, why would he have to? He could simply use compulsion to subdue her. It would explain her uncharacteristic meekness in regard to him. As for Faile, he wouldn't have to fool her. They were only together for half an hour if that.

It might also explain the emotions Perrin smelled on him when he met him. They were contrary to the words that he was saying but no one other than a Wolfbrother would recognize that.

It would be ultimately ironic if Lews Therin's greatest general from the AoL turned out to be Rand's greatest general. Both eventaully betray him.

There are probably problems with this theory, but I thought I would throw it out here and see the responses.