I checked your FAQ's and tags and such, but couldn't find this question anywhere; I hope I didn't miss it! As we know, Catelyn once suggested that things would be far, far different if 'he fell into the arms of Margaery Tyrell'. I was wondering, with your knowledge, how do you think the War of the Five Kings would have played out if, say instead of sending Cat to speak to Renly, he went himself and fell in love with Margaery/married her after Renly's death? How do you think would Stannis react?
The what-if of Robb marrying Margaery is somewhat popular, but unfortunately I don’t think the idea is remotely feasible. The reason Robb sent Cat was that he couldn’t go himself, he was busy leading an army. And it took Catelyn weeks to get to Renly – there’s no way Robb would have ever taken the time to do so himself. Also, a king who comes to another king directly to request an alliance is, well, not much of a king. That’s what emissaries and ambassadors are for, otherwise you just look like a beggar. It would be both political and military suicide to replace Cat with Robb.
Furthermore, Renly left Margaery behind at Bitterbridge when he went off to deal with Stannis’s siege of Storm’s End. And Catelyn was with Renly outside Storm’s End when he died, 500 miles from Margaery. (And was immediately accused of his murder, along with Brienne.) If you’re putting Robb in Cat’s place somehow, he’s not in any position to romance Margaery any more than she would have been to ride back to Bitterbridge and be like, “welp, Renly’s dead (I didn’t kill him btw), what do you think about my son?”
Now, say you don’t send Robb instead of Cat to Renly, but you still want to match Robb and Margaery… Well, unfortunately right around the time of the Storm’s End siege and Renly’s death was when Robb was busy with the campaign in the Westerlands and had just won the Battle of Oxcross. He’s also about 500 miles from Margaery (though the travel distance would be even longer as there are mountains in the way) so there’s no way he’s going to her himself. So he’s not going to fall in love with her by meeting her, nor “fall into her arms”.
Though once Robb heard the news, could he have sent an emissary to the Tyrells as Tyrion did? Possibly, although he has to deal with the fact his mother is accused of either murdering Renly or aiding and abetting his murderer. Assuming that’s worked out somehow, you then have the situation of the Stark emissary (whoever it may be, probably not Cat) versus Littlefinger, trying to convince the Tyrells of which king Margaery should marry. And sorry to say, I honestly can’t think of any possible way the Starks are going to win here. Not only is it Littlefinger for goodness sake, but Joffrey already holds the throne. If Mace wants his daughter to be queen and his grandson to be King of Westeros, Robb is not the best option. Even if he was running a remarkably successful Westerlands campaign at the time, right about this point is when Theon takes Winterfell and cuts Robb’s legs out from under him. (And Robb then falls into Jeyne’s arms when he hears about his brothers’ murders, and so on and so forth.)
So really, the only way you can possibly get Robb and Margaery together is to have an incredibly different situation right from the beginning. Renly has to not marry her, which means he can’t have been conspiracizing with Loras to make Margaery Robert’s mistress and/or somehow never arrives at Highgarden after Robert’s death. Or Robb has to be a lot closer to Highgarden to meet Margaery, but considering the situation in the Riverlands prior to the Battle of the Whispering Wood and the freeing of Riverrun… well, it’s functionally impossible.
Maybe Robb could have been in Highgarden talking with the Tyrells regarding a betrothal, during the time Ned was Hand – and many new Hands would have taken the opportunity of their rise in the world to start matching up all their children with the best of Westeros, but for Ned that would require a complete personality transplant to make him a dynastic schemer like Tywin – so yeah, while it’s a possibility, you then have Robb in Highgarden right when Robert dies and Ned is arrested, so even if he marries Marg right there, he then has to sail home ASAP and raise his levies, and that changes the timing of the war so dramatically I can’t even figure what happens next. Especially if a Renly/Tyrell alliance is not happening but a Stark/Tyrell one is? It’s a very, very different war. (One that GRRM was not planning on writing at all, mind you, because he knew from day 1 the Starks were going to lose.) Though no matter what, Stannis always demands fealty from Robb, because he is the rightful king of Westeros, and “one land, one god, one king”.
Anyhow, short of changing the entire course of the War of the Five Kings (and of the books) from the very beginning, I’m afraid there’s really no way you can get Robb and Margaery together. When Catelyn wondered “If you had to fall into a woman’s arms, my son, why couldn’t they have been Margaery Tyrell’s”, it wasn’t a statement of possibility, it was just a hopeless wish like so many she had at that time, as valid as dreaming “that Bran was whole again, that Arya and Sansa held hands, that Rickon was still a babe at her breast. Robb, crownless, played with a wooden sword, and when all were safe asleep, she found Ned in her bed, smiling.”
