RJ has stated that Osan'gar is Aginor. He said that in an interveiw when he apparently got tired of the question of who the 'gars were. Aran'gar is Balthemal, Osan'gar is Aginor.

Now, It seems very safe to say that the only "forsaken" in favor now are Demendred and Moridin, who I'm pretty sure is Ishamel(but that's not necessarily relevant). It does seem to follow that any forsaken "brought back" would be placed under Moridin (who has been named Nae'blis according to Mogie) or Demendred.

Dashiva, being an Asha'man, is by definition under Demendred, if Taim is Demendred. You can see through their reactions at key moments that this is indeed the case. In Message From the M'Hael (p306), Rand is thinking about what he has learned, "One in fifty mad, and more to come." RJ writes on the same page:

He had asked once, warily, where he knew the answers would be true, how to cleanse the taint from saidin. And got a riddle for answer. Herid Fel had claimed the riddle stated "sound priciples, both in high philosophy and natural philosophy," but he had not seen any way to apply it to the problem at hand.

Rand, who is slowly succumbing to Alzheimer's, speaks this aloud in front of Narishma, Torval, Morr, Hopwil and Dashiva. All of them are hopeful except Dashiva. "That would be wondrous", Hopwil says. But Dashiva looks "poleaxed". Of course he does. He's freakin' Aginor. Aginor the scientist. Aginor who probably sent the Gholam to kill Fel (and don't ask me how he knew, there are Darkfriends everywhere) because he had found a way to cleanse Saidin. Aginor probably recognised Rand's reference to the finns, "He had asked once, warily, where he knew the answers to be true...". This reveals that Rand asked the finns in TDR how to cleanse Saidin. If Aginor (Dashiva) figured it all out, he obvioulsy went to Taim (Demendred) with this imformation as soon as they returned from monkeying around with the Seanchan.

So Demandred and Aginor decide it's gone too far. It's time to off the Lord of Chaos. But they screw it up. Not for lack of planning, but because Rand is far too important to the story to just kill off, that and he's Ta'veren. So Rand is prepared to scour the Earth for these Mofos when Taim comes to see him.

Rand knows he's been channelled at from two sides. Then Taim has a very interesting way of wording what he saw above (Rand's quarters), "I cannot express my joy at finding you alive after seeing what I did above." Hello. What? It can be read two ways. "I cannot express my joy at finding you alive (because I'm happy or because I am not joyus at all I want you dead you bastard?) after seeing what I did (what 'I did see' or what 'I did do' as in blowing up your bedroom because I want you dead all of a sudden?)above."

Then comes the clincher. Rand tells Taim to add Dashiva to the list of deserters. Then adds that he wants Dashiva's head on the Traitor's Tree. Taim is shocked, "Dashiva?" he asks. Well of course he's shocked. Rand wasn't supposed to know about Dashiva. Taim can tell Rand about the others that were in on it, because Dashiva/Aginor can just kill them when they get through the gateway and put their heads on the Traitor's Tree. But now Taimendred has to kill Aginshiva, or else come up with some pretty good excuses.

Of course, Rand knows all about this. That is why RJ wrote Rand and Taim's confrontation from Min's POV. Rand knows he has to cleanse Saidin pronto and that the forsaken are on to him. He's smart. He knew when Asmodean and Lanfear were creeping on him in the Aiel Waste, he knows that Aginor and Demendred all up in his mix now, only he thinks it's Asmodean istead of Aginor (remember Rand has seen Asmodean's talent for making a disguise when Asmo was Jasin Nateal). Rand also thinks to himself earlier in PoD that he has to find Nynaeve because he wants to talk to her about cleasing Saidin (perhaps by using the Sa'angreal in Cairhein and Tremalking -- Which RJ mentions in his signature "There are no beginnings" intro). Also, Egwene dreams of Rand (p308) wearing different masks until one of the "false faces" is no longer a mask, but actually him. This foreshadows the cleasing of Saidin and a more sane Rand, it also goes along with Cadsuane and Sorilea's plan to teach him laughter and tears.

Rand's suspicions about Taim as well as his need to cleanse Saidin should play out in the climax of next book. With the Aes Sedai being bonded, Logain reappearing in the exact position Cadsuane described to weild Callandor (though Rand only needs to bond one more AS to weild it himself and Elayne has always had a 'bond Rand' fetish), and possible dessention between Aginor and Demendred (remember Taim has to kill Dashiva), Elayne in Caemyln (w/Aviendha at a time when Rand is travelling with Min and needs to see Nyneave -- lookout Rand.) I believe that Rand will be doing exactly what what he told Taim, Jumping around a lot. That should make book nine damned interesting.

Finally, to those who think that Dashiva is acting the way he is because he's insane, I offer you this: Remeber the last time we saw Aginor? Way back in tEotW. Remember how insane he was? A result of being only partially sealed. Why that same insanity isn't showing now in Moridin (Ishy) or Asan'gar (Balthamel-Halima) I can't explain, unless The DO restored their sanity and Aggie is just a good actor. I can't explain everything.