What if Oberyn won the duel?

[TimJames]

During the sack of KingsLanding, Elia Martell was raped and murdered by Ser Gregor.

Fast forward a few years, and her brother Oberyn Martell is fighting Ser Gregor in a duel. Nominally to champion Tyrion in the trial by combat, but really to avenge his dead sister. Gregor killed his opponent, but Oberyn got the last laugh by poisoning his sword and making sure Gergor died a painful death.

But what if Oberyn didn't lose the duel?

What would be different in the story if Oberyn was able to defeat and kill Gregor during the duel?

[King Tyrion I]

Tyrion would be free ot the verdict of kin(g)slaying. That's quite important.

[Seaworth'sShipmate]

Tywin would have been humiliated but Cersei still would have tried to kill Tyrion

[King Tyrion I]

Tywin would have been humiliated but Cersei still would have tried to kill Tyrion

I fear so. Especially about the killing part.

[Good Guy Garlan]

Tyrion would have taken Oberyn up on his offer to go to Dorne, mostly to be away from Cersei and any killing attempts of hers, I imagine.

My favorite bit of speculation is that Tyrion ends up getting involved in Arianne's Queenmaking plot. Since Oberyn didn't die, the Sand Snakes aren't fired up, so Arianne needs another partner in crime. And let's be honest: as the heir of CR and Myrcella's doting uncle he would be a more valuable ally than the volatile Sand Snakes. Plus, he's smarter and maybe they don't get caught by Hotah.

Elsewhere, with Tywin alive everyone from Stannis to Euron to Littlefinger would have a harder time attempting funny business. Aegon, in particular, probably gets screwed trying to reach Meereen.

[MegaTechPC]

I imagine Tywin would still be alive had Oberyn won (at least until Oberyn assassinated him). That is, of course, unless you believe the poisoning theory put forward by many...

[TimJames]

But what if Tyrion decided to kill his father anyway?

[Arya Weinergaryen]

If Tyrion is proven to be innocent, then he is not rescued by Jaime the night before his execution, and may not learn the truth(yet) about Tysha. So he doesn't, at this point, kill Tywin, and does not have to flee. He dosent help Jorah. Tywin force Cersie to remarry.

[TimJames]

If Tyrion is proven to be innocent, then he is not rescued by Jaime the night before his execution, and may not learn the truth(yet) about Tysha. So he doesn't, at this point, kill Tywin, and does not have to flee. He dosent help Jorah. Tywin force Cersie to remarry.

Just because he doesn't need rescuing does not mean Jamie would not tell him the truth. If that happens, he would still probably kill Tywin.

[Bryanfury]

Varys murders Tywin himself

[Liz Stark-Targaryen]

Varys murders Tywin himself

^ This. Varys is making big moves. The Old Lion has to go... no way can Varys get his mummer's dragon into place with Tywin Lannister as Hand.

[Sword of the Morgan]

It would have been awesome.

[BRANDON GREYSTARK]

Tywin would try to get Tyrion sent to the wall .

[JonCon's Red Beard]

Tyrion and Doran would be discussing the Dwarf's penny.

(actually, Tyrion would be quite happy in Dorne)

[Faint]

The event that caused a sea change in King's Landing was not so much Tyrion fleeing but Tywin dying, and as subsequent events have borne out, Varys never really needed Tyrion to do the deed.

My own take is that had Oberyn won, it would have very much lessened the impact of Tyrion going forward. He would have probably spent the rest of his days pleasantly drunk and whoring while in exile in Dorne.

[Kaguya]

Tywin probably would have killed Oberyn for humiliating him.

[TheRevanchist]

Tywin probably would have killed Oberyn for humiliating him.

Tywin was very smart and he called Oberyn at KL because he needed as many allies as possible against Stannis. Despite being humiliated, he wouldn't open an another war.

What would have happened though is that he would have send Oberyn to Dorne (because otherwise Obi would have killed him) and Tyrion would have gone with Oberyn (because otherwise Cersei would have assasinated him). And then obviously, Varys would have killed Tywin (similarity to how he killed Kevan) because Aegon would struggle more to come to throne with Tywin there, and because he hates Lannisters.

[Aemond's Eye]

Oberyn would have probably publicly said he'd killed the beast but not it's master or something, as presumably Gregor wouldn't have said the name. I think Oberyn had already poisoned Tywin so would have found some pretext to return to Dorne, and brought Tyrion with him.

Oberyn had already spoken with Tyene in regards to the Queen Myrcella plot. I expect that he then takes this forward to Arianne and/or Doran, along with Tyrion. (Do they still send Lady Nym as the Dornish seat on council?)

Aegon's landing would be interesting. I don't see Oberyn taking it lightly if he doesn't believe the lad to be his nephew.

Time wise, it's a pity Oberyn couldn't have lived then headed straight for Mereen. I imagine he'd have gotten there before Quentyn could have, and perhaps that goes differently...

[Lord Lannister]

Tyrion's position in King's Landing isn't viable anymore by any means. Cersei will pull out all the stops to remove it and Tyrion had little influence left before the trial. As mentioned before he could very well take Oberyn up on his offer for sanctuary in Dorne. It makes sense, not only would it get him out of immediate harm's way, but would put him in a position to hold Myrcella as a quasi-hostage as it were to keep Cersei honest. By all accounts Myrcella seemed cordial, perhaps even fond, of her uncle despite it all.

Oberyn's actions if he lives will be a huge wild card. He avenged his sister, but seems likely to set his sights on the man behind it all, Tywin Lannister. I shouldn't be surprised if Varys gets wind of this and aids this endeavor in some way. I could very well picture Oberyn walking in on Tywin on the privy one evening.

Dorne is another wild card with the addition of Tyrion to the game and the removal of Arianne and the Sand Snakes desire for revenge. I wouldn't see Arianne moving against her father immediately as failure to act on his death seemed to be the final straw that broke the camel's back as it were. If Oberyn dies killing or trying to kill Tywin, I could see the plot moving forward, if a bit belated. By all accounts Tyrion would be glad to use Cersei's own daughter against her and would have to be included by his proximity to Myrcella.

So in short, this question doesn't have an easy answer as it opens a whole can of worms, each one bringing a new question to the table.

[Mithras]

Since I believe Oberyn poisoned Tywin, Oberyn/Tyrion would return to Dorne and wait for Tywin to die from poison.

Arianne would not attempt the Queenmaker plot but maybe Oberyn would. In that case, Doran would send him to bring Dany back under the cover of sending him to exile again with Tyrion.