Enter House Martell (Gaius, any Dornish)

[oberyn]

As Oberyn looked out of the palace, looking out to the formidable threefold gate he spied a black raven fly past. A letter, but from whom. It was not long before the letter was brought before Oberyn. He inspected the letter, the kings seal. What did that boy want? He removed the seal and read the letter. The letter detailed how the King demanded that Dorne fulfilled their agreement and raise arms to defend kings landing, Oberyn smirked and tore the letter into pieces.

"The Lannister puppet wants us to go defend him from Stannis Baratheon, son!" Oberyn let out a roaring laugh, how naive of the Lannisters, Myrcella was their hostage now, once the King was defeated the Nymeria would return to Dorne.

Another servant entered the room soon after handing over another letter, this time it came from one of the many spies that the Martells had employed. Being so far away from mainland westeros, it was difficult to keep up on events of the realm. The letter detailed that Robb Stark had marched on Kings Landing and Ser Gregor Clegane had retaliated and attacked Winterfell. This news greatly interested Oberyn, he wanted revenge for Elia.
"Son, the monster has launched an attack on Winterfell, what council would you give? You're old enough now son, I will take you to war with me when the day comes."

[josh]

Gaius stood a few steps behind his father, enjoying the rather moderate temperature that Sunspear was experiencing. It was nice, in such a climate as theirs. Resting his hand on the pommel of his long-sword, he turned at the sound of a servant entering the room bearing a letter for his father. Patiently, he waited to see what news had been so urgent that it had been brought almost immediately to their attention.

His fathers comment on what the letter contained and subsequent laughter caused Gaius to laugh as well. The idea of a Lannister demanding anything from House Martell was ludicrous. Once he'd got control of himself again, he took a second to consider what that meant. The boy King was in dire straights and expected them to marshal their armies and reach King's Landing in time, regardless of the fact that the only place farther from King's Landing was the North.

His father's comment about The Mountain caused his blood to boil. The foul beast that had killed his cousins, dashed them against the wall like trash and raped his aunt...He would die a long, painful death for that. Him and his master's both. Taking a moment to reign in his temper, he considered his father's request for council. To march on Winterfell offered little down-sides besides the chance of defeat, yet not taking the chance left them with the probability of a long wait for vengeance. "I say we marshal all our armies, every last man we can scrape together and we go north. We go and we slaughter every man fighting for The Mountain and send his head to Tywin Lannister. We've waited long enough and I think this may be the best chance we have, with most of the Lannister armies stuck in the South." He said all this in a quiet tone that was brimming with repressed rage.

[oberyn]

Oberyn hated Gregor more than any other man, he wanted to stain his hands and spear red with his blood but would defending the north be a viable option? He would have to march his army across a vast land and back. By the time they got there Gregor may have already won and haul himself up in Winterfell and use its impressive defences against them. Dorne had no siege weapons either...

Yet, there was another option. With the Mountain and the Lions away, Casterly Rock would be lightly defended and defended by no one of importance, meaning that their knowledge of warfare would be limited.
"I would love to march north, son. Ser Gregor needs to die by our hands, not some Stark wolf. We could attack Casterly Rock, but then again, our siege equipment would be limited and it will have impressive defences."
Oberyn stood in silence as he gazed out over Sunspear, the Rock would be hard to capture and even harder to hold, this also opens Dorne up to attack from anyone who wanted to take it. He ruffled his hair and decided.
"We will march North together, I will show you how war is done. Then you may spread your wings, and lead armies alone."