Well, what I have to say isn't very specific. It's more on the whole general topic. Many people believe that Taim is Demandred and that Verin is a forsaken or Darkfriend. We've had evidence to suggest that such things have happened, even if Taim and Verin aren't what we think they are. Given the powers the forsaken have, or have access to (mindtraps, compulsion, etc.) and the tendency a lot of characters have to disappear, it could be anyone. Even people we firmly believe to be on Rand's side could be under compulsion (Dobraine, for instance). Because of the Taint, we're not even sure Rand is good anymore. Is anyone? I suppose the only characters safe from this suspicion are POV (Point of View) characters, who think in ways of helping Rand (as rare as these people are). I think we would know if a POV character was compelled remember when Moggy compelled Nynaeve and Elayne?