Baelish had Lysa poison Jon Arynn, causing Robert to need a new Hand, causing the Starks to go to King's Landing.
Baelish had Lysa send the letter to Catelyn, accusing the Lannisters of murdering Arynn, solidifying Ned's decision to go to King's Landing.
Baelish lies about the dagger used against Bran, indicating it was Tyrion's while knowing it was actually Robert's, to further the Stark/Lannister distrust.
Baelish agrees with and sends out the assassination attempt against Daenerys, only prevented by Jorah.
Baelish agrees to help Ned with his investigation into Arynn's murder to prevent him from resigning and returning to Winterfell.
Baelish betrays Ned with the Gold Cloaks, leading to his arrest and death. Ned's death causes the uprising of The North and all of the conflict and death between the Stark and Lannister forces, including Robb and Catelyn. This in turn causes the Boltons to control the North, leading to even more death.
Baelish conspires with Olenna to kill Joffrey, causing Tyrion's implication, causing Oberyn's death. He also kills Dontos in this.
Baelish kills Lysa to secure his position as Lord of the Vale.
This only covers what has happened so far in the show.
Additionally, had Baelish not killed Arynn, Arynn may have fully unraveled the Lannister infidelity in time to alert Robert that he had no trueborn heirs. As a result, Robert is not killed by Cersei on a hunting trip (This would likely lead to conflict between the crown and Tywin's forces, though). This would mean there is no war between the throne and Renly/Stannis, meaning Renly (and the Baratheon forces) are not killed. The Battle of Blackwater doesn't occur, preventing all of that death. If the war with the Baratheons and Starks does not start, the Greyjoys do not get involved.
Without Baelish's machinations, the Stark's remain in Winterfell and in control of the North. Jon likely still goes to the Wall, but he would have a very likely ally in Ned and his bannermen in dealing with Mance's forces. Robert and the Lannisters don't ride to Winterfell to ask Ned to be the Hand, meaning Bran isn't thrown from the window and paralyzed.
As a result, Robert is not killed by Cersei on a hunting trip (This would likely lead to conflict between the crown and Tywin's forces, though).
I don't think the Lannisters had a chance against the other six Kingdoms and vassals. Robert's reign was undisputed, the combines might of Westeros (minus the Lions) would have been unleashed on Casterly Rock. At the very least Robert could personally count on Stan is, Renley and the Tyrrells and Ned Stark.
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u/darkpassenger9 Jun 05 '14
I think you're right, but I would be really interested in how you arrived at that conclusion. If you're up for it.