If Rhaegar won and Lyanna survived, would Dorne be threatened, and would they justified in feeling that way?

[Bright Blue Eyes]

Oh, that Viserys. I assumed you to talk about Rhaegar's brother.

Anyway, even Viserys was about a million times smarter than Rhaegar. At least he married a women from a less powerful House than his first wife.

[Wmarshal]

He was, my main point those posts was that it is better to try to remove a threat of civil war then do nothing like Viserys.

[King Viserys Targaryen IV]

If Rhaegar had defeated (killed) Robert on the Trident and won the battle Rhaegar immediately returns to King's Landing and calls a Grand Council and takes the Iron Throne for himself. Having his father and his father's spy Varys executed.

King Rhaegar has Lyanna brought to the Red Keep and proclaims that he has 2 Queens and Lyanna's son (Viserys Targaryen) is born a Prince and second in line for the Throne.

Rhaegar calls for a truce and a meeting with Ned Stark, Jon Arryn and Hoster Tully to try and create peace.

The rebels, having lost a great battle and their number one claimant, realizes that the Mad King is no longer on the Throne, agree with the conditions that none of them are to be executed and they would be allowed to return home and continue there Lord Paramount duties.

Lyanna (she died in the regular time line and I would suspect that the same outcome would happen here) begged Rhaegar (who was at the birth of his son) that Ned and the rebels not be punished and made Rhaegar promise to protect Viserys (Jon) and let him know the Starks.

The lone stand out to this is Stannis Barantheon who refused to kneel and surrender Storm's End after the Rebels put down their weapons. Storm's End was eventually taken and Stannis is executed. Jon Connington is named the new Lord of Storm's End and Lord Paramount of the Storm Lands. Stannis' brother Renly is sent to be a ward of Jon Arryn at the Eyrie (Rhaegar hopes to gain Jon Arryn's trust) and Renly is eventually given a hold in the Vale.

Rhaegar, knowing that he had a large part in starting the civil war wants to bring his Kingdom back together agrees to let the Rebels return home and seeks to make amends with all of the realm.

To bring the Lannisters (gold) back into the fold he releases Jaime from his King's Guard duties (for Tywin) and names Tywin the Hand of the King. He asks Tywin to marry Cersie to Hoster Tully's Son and Heir to the Riverlands Edmure Tully.

To protect Jon from any threats from Dorne (and to gain Ned's loyalty) he offers to foster Viserys (Jon) at Winterfell fulfilling his promise to Lyanna and sets up a marriage of Rob Stark to Daenerys Targaryen (now his ward, along with her brother Visery since their mother died in child birth)

While in Winterfell, Prince Viserys (Jon) discovers a dead mother Direwolf and her cubs. He gives each Stark child a pup (with Ned's permission) and keeps a white pup for himself in honor of his own Stark Heritage.

For his brother Visery, he sets up a marriage to Margery Tyrell rewarding the Tyrell's for their loyalty to the Targaryen during the Rebellion.

To reward Dorne for their loyalty (and to make up for Lyanna) Rhaenys Targaryen is sent to foster at Sunspear and arranged to marry Quentyn Martell.

For his son Aegon, Rhaegar has arranged a marriage to Arianne Martell to tie Dorne even closer to the Throne and to please Aegon's Mother Elia.

For Viserys (Jon), who the King has a soft spot for because of his resemblance to his mother, Rhaegar let's him marry for love. While Visery (Jon) was in Winterfell he falls in love with Sansa Stark. For Sansa Viserys (Jon) is the Prince/ Knight that she has always dreamed of, and to Viserys (Jon) Sansa is a link to the North and his mother that he never knew. He marries her and Viserys (Jon) is named Lord of Dragonstone.

Later when the Greyjoys rebel against the Throne, Rhaegar and Ned become close friends during the campaign to take back the Iron Islands.

After the Greyjoys defeat, Rhaegar has Balon Greyjoy executed and gives the Iron Islands to the North and places it under the watch/ protection of Winterfell. Theon is sent to be Ned's ward along with his sister Asha.

As a reward to the Mormont's for their valor during the rebellion Ned Stark grants the Iron Islands to Joer Mormont, who passes them to his son Jorah (who gained notoriety during the Greyjoy Rebellion) while he continues to over see Bear Island.

With the relative peace and prosperity of the Kingdom during his time on the Throne, Rhaegar sees to make his Kingdom stronger to aid the Prince who was Promised when the time comes.

He creates a standing Royal Army led by Heir to Casterly Rock Jaime Lannister. Made up of the scripted men from Bannermen of all of the Lord Paramounts, the men are paid handsomely by the King's overflowing treasury (run by Tyrion Lannister) and included the finest warriors of the Seven Kingdoms.

At the request of the Benjen Stark, Lord Commander of the Night's Watch, Rhaegar has been supplementing the the Wall with rotating troops from the Royal Army and the waters are patrolled by the Royal Navy.

Lord Ned Stark has taken to re-populating the New Gift, with the increased security provided by the bolstered Night's Watch the initiative has begun to prosper. Ned plans to build a new hold to over see the area that will be held by his son Bran Stark.

When King Beyond the Wall Mance Ryder pushes his 100,000 men to the Wall they are easily defeated by the combined forces of the Wall and the Royal Army. Mance and his would be officers are executed and the remaining are wildings turned back.

So that brings Westeros to the time of the Red Comet. The Kingdom is in better shape as well as the defenses of the Wall and the Kingdom as a whole. There is no civil war and because Rhaegar believes in TPwwP, he has prepared Aegon and Viserys for the upcoming tribulations. But Daenerys never hatches the Dragons.

The question is, how important are the Dragons to the upcoming war?

[Staenerys Stargaryen]

Oh, that Viserys. I assumed you to talk about Rhaegar's brother.

Anyway, even Viserys was about a million times smarter than Rhaegar. At least he married a women from a less powerful House than his first wife.

Rhaegar took women from houses that are demographically just about as far apart as you can get in all of Westeros. But I actually think the Stark and Martell houses are kind of like North Good and South Good. Both are said two be able to field formidable forces and fight for what they believe to be right. Both deal with harsh seasonal weather conditions, although opposite in nature. They both hate the Lannisters.

Anyway in regards to which house is more powerful... pretty hard to compare. Its not like there could be a battle between House's Stark and Martell that didn't involve the entire realm. Power in Westeros is in some capacity relative to who you are ruling over, and also who you fight against.

Rhaegar was a very smart man, especially in terms of Westeros standards. He was a little over superstitious. He made some bad decisions, but so has everyone else to ever have lived. Rhaegar died via Bobby B's war hammer to the chest and paid for his less than good decisions. But good for him for manning up for his actions and meeting the enraged Stag in the field.

If Rhaegar would have won that would only leave more dragons then the existing Dany, Aegon, presumably Jon, and any other would be pretender to contend for the throne. But then there would be no room for Stannis in the mix... what a tragedy! Stannis fans would have no idea what to do with themselves.

(BTW:I like Stannis (I like all ASOIAF characters))

[Bright Blue Eyes]

snip

House Stark is one of the strongest Houses in Westeros. Furthermore, they had an alliance with Tully, Arryn and Baratheon, with Lannister looking to jump into bed with them as well.

On the other hand, House Martell is the weakest Great House, together with Greyjoy. Furthermore, they had just reignited the feuds with House Tyrell and House Yronwood.

That's about the most ironclad situation to start a civil war over that's even theoretically possible.

[Rorey Targaryen]

Political Implications

The problem that arises is when you involve Jon Snow and any other children that Rhaegar would have had with Lyanna (if he took her as a second wife).

Jon would be better connected than Aegon and Rhaenys (his Uncle (Ned) hold/ will hold the title of Lord Paramount of the North, his Aunt's (Catlyn) Father would be Lord of Paramount of the Riverlands, and Ned would have also been raised by the Lord Paramount of the Vale). Baratheon connections in the Stormlands would be unclear given the fact that Lyanna was betrothed to Robert and Jon would likely have the support of the Reach given the enmity between the the Reach/ Tyrells and Dorne/ Martells.

This, in addition to the fact that Dorne was one of the most disliked Kingdoms in Westeros would have given Elia cause to worry about the status and safety of Aegon. Rhaegar's treatment of Elia and pursuit of Lyanna could have been seen by the people of Westeros as the future King casting aside his first wife because she was "unworthy" of him for a younger, more beautiful Queen from a much more favored Kingdom. Jon would be second in line to Aegon and at least 4, maybe 5 of the Kingdoms of Westeros would prefer a 1/2 Northern King as oppose to a 1/2 Dornish King. Regardless of whether the Starks would endorse it or not, there would be people trying to kill young Aegon to get Jon on the Iron Throne.

IIRC, isn't Elia referred to as a "Tigress" when it came to her kids (frail and sickly as she may be, she stood up to Gregor "the Mountain" Clegane to protect Aegon). She was also said to be smart/cunning/clever/witty so I would doubt that she would stand by and do nothing whilst there was an open threat to her son's life and inheritance.

How I imagine events to go down.

This scenario would happen some time after the end of Robert's Rebellion.

Elia would befriend Lyanna, maybe also Ned and the other Starks, and act lovingly towards Jon.

Elia would call up Oberyn and he would either poison Rhaegar and Lyanna with a substance that would kill them slowly (so as to not immediately rouse panic/suspicion) or would kill them himself but make their deaths look like an accident. Oberyn would stay in King's Landing to protect Aegon and Rhaenys.

When Rhaegar and Lyanna die, Aegon will be crowned the new King and Elia would be the Queen Regent, Doran gets called in to be the Hand of the King and Oberyn in made Lord Commander of the King's Guard. This is to ensure a strong Dornish presence in King's Landing.

Elia would take over as young Jon's parental guardian (she's a very maternal figure). She would be as loving to him as she is with her own children and raise him to be close to Aegon and Rhaenys and to be his brother and sister's keeper. She would tell him about the forces that would want to see his brother dead so that he could be King and would influence Jon to be fiercely loyal to Aegon and Rhaenys and fight anything that would act to drive them apart.

Basically, Elia is smart enough to know that despite all of Jon's connections, he can't be blamed for other people's agendas or his parents' actions. She will raise him to to be Aegon's fiercest champion rather than his greatest challenger.