If Theon doesn't take Winterfell, the Ironborn invasion would have been a simple reaving like they've done thousands of times for thousands of years instead of the huge clusterfuck it precipitated. Robb probably would be on the Iron Throne by now.
Robb probably would have taken Casterly Rock and Lannisport as Tywin was turned back by Edmure Tully at the Battle of the Fords. Tywin would have rushed to Kings Landing to meet up with the Tyrells and beat back Stannis to protect the throne. After the Battle of the Blackwater, Tywin would have to decide how to take back the West as losing the West would be a great slight on the Lannister name he has worked so hard to elevate. Thus, Tywin wouldnt have been so triumphant and he wouldnt have been able to broker the Frey and Bolton treachery at the RW. The Riverlands would have been consolidated under Robb and Tully rule with the Frey alliance intact and no Lannister host outside of KL.
Basically the Northmen would have easily repelled the Ironmen with all the fighting men that are coming out of the woodwork to back Stannis and the Boltons now. A couple of ravens from Winterfell would have raised at least 5000 men from the North to fight the Ironmen once it was understood that this was an invasion. My only question is if White Harbor finished building its fleet, would Robb used them to invade the Iron Islands and how do they get those ships to the west coast of Westeros. There is no way to sail them south past Dragonstone, through the Stepstones around the Arbor and the Sheilds, all enemy territory with fleets of their own. But knowing the Northmen, I see them carrying them over land. This would make Robb, King of the North, The Riverlands, the Iron Islands and the Westerlands. With Joffrey, King of the Crownlands, the Stormlands, the Reach and Dorne.
This is where it gets interesting. Knowing now the Vale has stayed out of the War because LF is calling the shots, how does this change his plans? Does he continue his assassination of Joffrey with the Tyrells? Do the Tyrells go through with it? Of course, he wouldn't have been named Lord of Harrenhal, with Robb having cleared out the Lannisters from the Riverlands, so he wouldn't have been able to marry Lysa, thus he wouldn't have killed her because he'd need her to make the Vale do what he wants. But if he went through with the assassination, he would probably just deliver Sansa to Robb and get Lysa to join Robb. He probably could deliver the Tyrells as well, who wouldn't push for Margerey to marry Tommen after Joffrey's dead, as Tyrells obviously have no love for Lannisters. Would they push Robb to break his bethroval to the Freys in order for Robb to marry Margerey? Or would Martells want Robb to marry Alianne to secure Dorne? The Lannisters would be isolated with only their marriage alliance with Dorne through Myrcella, but she would be more of a hostage and Dorne would be happy to turn on the Lannisters for what they did to Elia. This is how Robb could get to the Iron Throne, starting with the North, reclaiming the the Riverlands, conquering the Westerlands and the Iron Islands, brokering alliances through LF with the Vale and the Reach and allying with Dorne. I don't see the Stormlands backing the Lannisters with everyone else siding with Robb, especially since the story of Lannister incest would have the honor of the Starks behind it, so they will know Tommen is not a Baratheon. Stannis would be an afterthought as he would be stuck on Dragonstone with no Wall to run to.
i just dont know what happens when the NW sends a raven to Robb saying there is a wildling host moving towards the Wall and confirmed sightings of wights and whitewalkers? But if Stannis turned back The Wildling host with 2 or 3000 men, I'm sure those Northmen who threw back the Ironmen could have defeated the wildlings while Robb fought in the South.
As you can see, if Theon doesn't take Winterfell, Robb would more than likely have won the War of the Five Kings and won the Iron Throne. The question is would Robb want the Iron Throne? I see him taking the West and the Iron Islands for invading the North, but I see him allowing Stannis to be King of the Stormlands. i know, he'd die before giving up his claim to all 7 Kingdoms. Maybe he'll kill Stannis in battle but marry Bran to Shireen (two broken children) to rule the Stormlands. He'd let the Reach and Dorne be independent and keep his bethroval to the Freys, since a Stark keeps his word. He could marry Arya to Tristan Tyrell to secure the alliance with Dorne and marry Sansa to Willis or Edmure to Margerey to secure the alliance with Reach.
Edited by KingofSothoryos, 08 September 2013 - 05:44 PM.