I've been working on a theory:

We know from Admiral Taylor's journal that Wrathion was in Spires and had pissed off some Ogres in Nagrand where the Ogres have been unearthing titan relics and using them to create the breakers. They also opened up the Vault of the Titans, exposing a titan relic of great power which we help the Steamwheedle recover during the quest "A lesson in Archaeology".

During the garrison campaign, we come across a quest chain wherein the Iron Horde is excavating in Gorgrond and comes across an artifact called "The Heart of Gorgorek" which is a massive circle leaning up against the wall. Looking at this circle, I think that the titan relic located in Nagrand would fit in the middle of this thing. After we collect it, we put it in a chest where it sits in our garrison and pulsates. (we've seen a pulsating heart in a chest somewhere before). It is eventually stolen and used to make Gorgorek who we slay.

While Wrathion was not in direct control of the above events, I believe he's been stearing things in this direction for a long time. I think the steamwheedle preservation society works for him. I think he told the goblins to get us to get the artifact since he couldn't himself (he doesn't much like getting his hands dirty anyway). I think he's been hunting relics of titan power this whole expansion, by using others to do his bidding. But most importantly, I think he is impersonating Khadgar.

I think he recreated Atiesh and imprisoned the real Khadgar (probably in Karazhan) and has been using him to guide the horde and alliance to complete his goals.

There was a scene during the legendary questline after Wrathion eats the heart of the thunderking where he says "It is gone, I don't remember any of it! Oh none of them remember it! The irony". The only time I've seen someone talk about remembering events that others don't (appart from crazy people) is during time travel episodes.

I think