There are some more interesting points about the "Taim is really Demandred" theory. I don't know that I believe it, especially since RJ doesn't seem to support it (as Tamyrlin says) however, there must be more to Taim than just your run of the mill false dragon turned M'Hael. First, LTT's ravings. He only really goes off like that when Taim is around--nothing of the sort appears in the presence of Lanfear, Asmodean, while chasing Rhavin, etc. While this might seem to counter the argument for Taim=Demandred, remember that Demandred's hate for LTT is something special, and that LTT would most likely feel a bit of the same for Demandred. LTT also aludes to the contempt that Sammael and Denandred had for the honors he gave them--he annoyed them so much that "they sold their souls and went over" (I hope that quote is accurate). LTT mutters that quote (I think) in Taim's presence. Also, look at Taim's reaction to receiving the pendants from Rand! He is angry at having the Dragon Reborn name him M'Hael--he is the M'Hael no matter what Rand al'Thor says. That somehow smells to me like the hate that drove Sammael or Demandred during The War of the Shadow. Samael cannot be Taim that simmply doesn't fit his style or him. One final point--during LTT's rantings in Taim's presence, he constantly refers to a "them" or "them all" he should have killed. That might be the Forsaken--he sealed them up rather than killing them with balefire (or perhaps something more tame). Certainly 100 male Aes Sedai could have done them in at Shayol Ghul, rather than sealing them inside. Maybe they didn't have time or something, I don't know, but I can't think of who "them" might be, otherthan the Forsaken.

Conclusions:

1. That was a long setup

2. Taim could be Demandred, or he could not--there is no direct proof. It is tantalizing to say that he is, since that idea does fit the facts rather well, but all that anyone has offered (including myself) is purely circumstantial.

3. Taim has to be somebody special. My pet wild theory is that he will become a Dreadlord/Forsaken kinda guy when Tarmon Gai'don comes around, taking some of the Balck Tower with him. RJ has foreshadowed new dreadlords, and where else can they come from? I doubt the DO can grant the ability to use the Source to people, and I don't think that the dreadlords of Trolloc War fame used the True Power. LTT may simply have insight into Taim's defection, and his reasons, or something like that. I know its a stretch, but you have to agree Taim is not in this for the Glory of the Light.