How it works: I ask a "what-if" question regarding the books. The next poster answers, then posts his own question.

What if Balon Greyjoy had accepted Robb's offer in A Clash of Kings?

Xenu's Paradox said:

Theon goes back to Robb, with his father's agreement. Robb continues to harry the Lannisters in the Riverlands and Easternlands. The Greyjoy fleet prepares to attack Lannisport all the while "raiding" south from the Isles. Because of this dual-threat, Lord Tywin masses his forces in stronger opposition against Robb, hoping to crush the Young Wolf. Edmure is able to hold Riverrun easily without having to ride out, and Tywin does not meet up with the Tyrells for the Battle of King's Landing. The BofKL lasts for days, as the Tyrell forces come up after Stannis has secured a foothold outside the city.

Meanwhile, the Battle of Lannisport begins, taking place on land and sea. Robb's forces attack from the north after he takes the Crag without being wounded (and thus never interacts with Jayne Westerling). The armies of Stark and Greyjoy are powerful, and most of the Lannister fleet is destroyed, but Tywin's forces are fighting with a stronger tenacity since it is now their home and capital being threatened. During the battle, Ser Gregor Clegane and a group of his "dogs" comes into direct contact with Robb and his bodyguards. Theon attempts to save Robb from being killed by Ser Gregor, and dies in the process. In the end Robb is seriosuly wounded and barely escapes with Dacy Mormont and the Small John. They beat a retreat for Riverrun, and the Young Wolf loses his first battle.

Back at Kings Landing, Stannis's forces are able to take the city but are under seige by the Tyrell's. Tyrion ends up dying as no-one comes to look through the wounded. Cersei orders Ser IIlyn to kill Sansa Stark before fleeing with Varys and her sons through some of the underground tunnels (because Varys does not want Stannis as King).

The Greyjoys are unable to capture Lannisport, and return to raiding the shorelines. Balon is not saddened to hear about the loss of his son, who he felt became too weak to lead the ironborn. Balon returns to Pyke, and dies shortly thereafter in a storm, at which point Euron Greyjoy comes back to Pyke and declares himself King of the Ironborn. He breaks the alliance with the Stark and wins the Kingsmoot. As Robb recouperates at Riverrun, he ponders what to do with Jaime Lannister (who was not released since Theon never "killed" Bran and Rickon). Cat is heartbroken, as she believes both of her daughters are dead, but with Robb in Riverrun she is unable to affect the release of the Kingslayer.

The Ironborn begins to attack the north, and take Moat Cailin, cutting Robb off from returning to the North. Tywin contacts Roose Bolton about making a deal for the Boltons to control the north if he switches sides, which Roose accepts. He gets word to his bastard son, who is only too happy to engage his bloodlust. The Boltons approach Winterfell and takes the castle, holding the Stark children as hostage against the other bannermen. Several northern "lords" throw their support behind the Boltons, as they begin to feel that Robb has abandoned the north.

The Hound is able to take Arya to Riverrun, and as he suspects Robb is willing to pay him a ransom but not take him under his wing. Unwilling to have anyone (even the Blackfish) fight against the Hound, he sets him on his way, but only after the Hound swears he will not attempt to group up with the Lannister forces. Cat is overjoyed that at least one of her daughters is still alive.

Robb, still injured, takes his mother's advice to marry Roslyn Frey quickly, to keep Walder Frey as an ally. Robb goes to the Twins for the wedding, but Tywin has again capitalized on Robb's loss (and several subseqent loses as his forces try to hold back the forces of the Lannisters). The Red Wedding ensues, only this time Robb, Cat and Edmure are held captive for the release of Jaime Lannister. The Blackfish relents, and Robb is forced to concede to the Lannisters. Robb has lost his kingship, his people, and Winterfell. The Starks are no longer considered Great Lords.

Meanwhile, Lord Tywin return to Kings Landing to assist the Tyrell's in taking the capital. Stannis in unable to hold the city against the stronger forces arrayed against him. Lacking his Onion Knight, who has gone missing in the Battle and not seen since, he fails in his attempt to flee the city. Captured by Tywin, Stannis is publicly executed for his treason, though many of his lords are pardoned (much to Joffrey's dismay). Joffrey decrees that he and his siblings shall not be Lannisters, cutting all ties with the Baratheons, the "family of Traitors."

Tywin waits for Paxter Redwyne's fleet so they can take Dragonstone. Joffrey (via Tywin) order that the Stark boys be sent to King's Landing to be wards (hostages) of the crown. Robb is welcome to stay at Riverrun, but is banned from returning to the North. What few northern lords that have remained loyal to the Starks finally turn their backs on them.

Joffrey dies at his wedding feast mere hours after marrying Margery Tyrell. It is whispered that his death is the curse of Stannis Baratheon. Littlefinger marries Lysa Arryn to get her to declare her peace with the Lannisters. He spends little time with his wife, instead traveling around the Vale and the regions around Harrenhall, his new seat. Shortly after the tragic murder of his wife by the singer Marillion (who is executed in turn), LIttlefinger offers his hand to Catelyn Stark, who decides to accept are Littlefinger arranges for her children to be his wards. Robb chooses to take the Black instead of being a fallen Lord. Littlefinger is able to install one of his Allies as castellan at the Eyrie, and moves into Harrenhall with Cat.

What if...Jon had not returned to the Wall at the end of A Game of Thrones?

Looks like nobody else wants to play, JJ. Guess I'll have to answer myself.

Jon becomes Lord of Winterfell. With him in charge instead of Bran, the Greyjoys find it much more difficult to sack the North. Jon is able to rally the troops more effectively, and come the Battle of Winterfell, Theon's troops are routed. Ramsay, disguised as Reek, is captured and thrown in the dungeons. Theon is sent to the Wall in lieu of execution, and Asha is kept as a hostage. However, the guards at Winterfell are unprepared for her martial prowess and her cunning, and she escapes. She goes to Roose Bolton in hopes of forming an alliance, but he has no intention of sharing the North with the Ironborn and has her flayed. Bolton then musters his troops to march on Winterfell, but Victarion, angered at his niece's death, intercepts him with his own army and the two hosts demolish one another. In the end, Roose has more men remaining and the wounded Ironmen are put to the sword. Roose, knowing that he can't hope to take Winterfell with his paltry remaining force, returns to the Dreadfort and fortifies it against the inevitable retaliation from the Starks.

Meanwhile, Theon 's actions are similar to Jon's throughout ACoK and ASoS, at least in broad strokes, for while his personality is much different from Jon's, he sees the true threat to Westeros that the Others represent. Like Jon, he becomes Lord Commander after the Old Bear's death, but unlike Jon, he accepts Stannis' offer.

What if Stannis had struck a deal with Renly and Catelyn in ACoK- Renly gets to sit the throne, while Stannis, as Hand, is the one who truly rules the Six Kingdoms, with the North belonging to House Stark?

JerusalemJones said:

Now that's an answer and a half!

Xenu's Paradox said:

The Lannisters would be defeated at the battle of King's Landing, but the alliance wouldn't last for long. Stannis would only ever have agreed to the alliance under extreme pressure from Melisandre, so would soon regret his decision and look for a way out. Renly and Margery would never have produced an heir, so the Tyrrells would have gained little for throwing their support behind Renly.

Fast forward a few weeks, and the court would be tearing itself apart with fresh intrigues. The Power vacuum would lead to a Lannister restoration in the South, whilst in the North, Robb would be busy taking his revenge on the Greyjoy's. Somehow, Littlefinger would come out of it all in a better position than ever, although he wouldn't become Hand as it would make him too obvious a target for eveyone else.

What if Nymeria had actually killed Joffrey on the journey from Winterfell instead of just shaking him up a bit?

What if Nymeria had actually killed Joffrey on the journey from Winterfell instead of just shaking him up a bit?

If Nymeria had killed Joffrey on the way to King's Landing. Robert would have had Arya executed for the murder of his son Joffrey. Angering Ned Stark and he retreats to Winterfell. In the process Tywin convinces Robert to declare war against the Starks. The Starks rallie their banners and Jon Snow never goes to the wall because he father comes back in time to stop him. Ned tries to march his force south and make a deal with the Frey's to cross the Neck. The Frey's betray the Starks and the rebellion is quashed before its starts. The Starks loss their lordship and it is give it to the Boltons.

What if Tywin wasn't kill by Tyrion?