I've often brought up the point in the past that I thought one of the things I imagined someone with Demandred's personality doing is that he would be obsessed with bettering Rand's achievements, and undermining Rand's efforts.

So in my opinion, Demandred was never far behind Rand through the series, corrupting his allies, coming up with better versions of what Rand gained.

Rand founded a training center for channellers? Demandred would have a pawn infiltrate it and create within it a much more powerful army for himself.

I never thought about the Aiel before, but Demandred has expressed his frustration with the fact Rand secured their allegiance ("cursed Aiel", "cursed Rhuidean" and so on).

I think Demandred has gathered an Aiel force of his own, to spite and mock Rand's Aiel followers. Are they channelers? Possibly. Maybe not all of them, perhaps all of them. We'll see. It's possible they include the male channelers who've gone to SG to die, and got turned to the Shadow instead. I'm not convinced either way, though it's either that or Aiel taken by the bleakness who got seduced, or turned.

I'm pretty convinced at this point that Demandred has assembled an "alliance" of his own (like apparently he had assembled his own group in echo to LTT's hundred companions.. these eighty and one, the one in question probably referring to Demandred himself). This will include Taim's Asha'man (I'm still sure Demandred is the mind behind the BT), the Red Veils, the remnants of the Black Ajah, perhaps Seanchan darkfriends, remnants of the Whitecloaks left behind by Asunawa, and who knows what else. Heck, it could even include the nation that's been ignored after all (Murandy, though it's very unlikely the Murandians will fight openly for the Shadow - they could still be sent to their doom in a move to create chaos among the Light.) I still think it's more likely the Murandians have been left alone because they're the last buffer between the Seanchan and Andor, and Jordan had something in mind there (like the Murandians allying with the Seanchan, and agreeing to draw the Andoran forces south by invading them, while the LB is already raging).