How could Robb have won Walder Frey back?

[Agent 326]

How could Robb have assured that Walder would be loyal?

Here are my terms that I would offer Walder Frey,

Merrit Frey gets Darry

The apology

Emmon Frey gets Casterly Rock when Robb takes it

Hosteen Frey gets Crakehall when Robb takes it

Harrenhal for Black Walder (why not, it distances him from his kin, gives him a place that is said to be cursed and Walder Frey's 5th wife was a Whent, however she died before she could give Walder children)

Petyr Pimple gets Nightsong upon Robb taking it

Edmure Roslin marriage

Symond Frey is made Master of Coin

Arya Elmar marriage is still in place

Perwyn Frey gets Rosby when Robb takes it

Marrying Catelyn to one of Walder Frey's sons or grandsons

Most of these choices are specific. I also am trying to balance the power between the many Frey factions. I could've given Darry to one of Cleos's sons but I chose against it because Emmon already got Casterly Rock and lord paramountship of the Westernlands some really powerful titles.  I gave Hosteen Crakehall because he is the first born of Walder's children by his third wife who was a Crakehall. I figured no matter what Master of Coin would go to a Frey I just didn't know which one. Steveron if he didn't die, but since he died I opted to chose Symond because he is a coin counter. Must I explain to you the Arya Elmar marriage, Edmure Roslin marriage, the apology, or Catelyn marrying one of Walder Frey's sons or grandsons. Petyr Pimple is married to a Caron which is why I chose to give him Nightsong. I chose to give Perwyn Rosby because his mom was a Rosby.

 

And this is against

Ramsay gets to marry "Arya Stark" though  it turns out that it is actually Jeyne Poole and she ends up motivating Theon to escape.

Roose Bolton is giving the title of Warden of the North, until Tyrion and Sansa have a son and after he has become a man grown. And at that point Roose will likely be dead and Ramsay will be Warden of the North and he won't be happy to have to give up being Lord Paramount of the North, Warden of the North and Winterfell.

Emmon Frey gets Riverrun and all lands and incomes.

Lancel is to marry one of Walder Frey's daughters/ granddaughters and he will get Darry. However he chose to forsake his marriage and Darry.

Daven Lannister will have to marry one of Walder Frey's daughters/ granddaughters.

Joy will marry one of Walder Frey's bastard sons. I don't remember which one.

Frey pies.

No one trusts the Freys anymore and being a Frey is an insult. Though House Frey wasn't very popular to begin with as they are basically a giant toll both.

A Frey Civil War 

 

The BWB starts to kill Freys and their soldiers (Petyr Pimple, Merrit, Raymun, likely a few more will happen in future books).

So which would you chose? Would you accept mine? Would you change mine?

[The Bard of Banefort]

Unfortunately, I'm not sure anything would have placated Walder at this point. Once it began to look like the North was going to lose, he probably started thinking of ways to jump ship. The broken marriage pact was just the perfect excuse. (I don't have the links, but I have seen people in the past claim that there were already signs of Walder and Roose being in cahoots with Tywin before then).

Something I think Robb could have done that doesn't get mentioned very often is to have had Jeyne married off to one of his bannerman instead of marrying her himself. Tyrion considers doing this with Shae, and Cersei mentions at one point that there were plenty of other women throughout Westerosi history who were either no longer maidens or pregnant with bastards that were quickly married to a minor lord as a cover-up. Robb had plenty of unmarried men in his retinue who most likely would not have minded being married to a pretty young woman who had slept with their king once. I'm curious if that would have been Catelyn's advice had she been there the morning after.