I think starting off with the peace summit would be the best option at this point considering two of our players are more aligned with the crusade then their "home" faction.
But I am up for whatever plot we use
For my own character, I will stick with being the representative of the Kor'kron Guard of Ogrimmar. (My spin on the Kolkron, they are loyal to the horde above its warchief, with Garrosh coming in as its new leader, the Kor'kron is there to make sure he is protected - Anyone who read Wolfheart would have seen that, but their main focus is its duty to the Horde)
Also to those who were in Northern, we might have run into one another IC in the past so I wanted to go into a little more detail.
I left the final details of Arthas's death hazy, but Gorejaw was among the remaining few to witness the fall of Arthas (Maybe not to the point that they saw what happened to Bolvar)
I imagined the Horde and Alliance finally came together long enough for a brief moment in order to take down the bigger threat.
Off course there was still two airships (After losing a few in the first push?), firing off at waves of gargoyles and backing up the land forces, more reinforcements coming in to hold the citdel against waves of waves of enemies, etc. (I picture a huge massive battle- Not some 10 or 25 man raid to end it)
Then when it was over...the Horde and Alliance looked at one another and just backed off for that day.
(In my personal story line, Gorejaw swore to take a tabard of a fallen paladin to his son/family)
So basically to the current players, do you want to establish they know one another?
Not saying they have to be friends or anything like that.
I imagine Thukk would stick out to Gorejaw, considering his profession and legacy of breeding war wolves.
Also the crew aboard the ship for giving them a ride to the higher peaks meant a possible run in with Wessly and tended by Selistria Dawnfire before his dispatch to Northrend.