Okay, here's a recap of what I pitched to Rel:
Dorne is ruled by a king in his prime who unfortunately has fallen pray to the terrible disease plaguing Westeros, the mad fever. He has several children, the oldest a daughter, second a son and then three more daughters. The son has been preparing to take his place eventually, guiding his father into much more militaristic directions than the king himself was inclined to, but the son has his father's ear and the king is confident he will make a good ruler. The disease however has forced the king to rethink the traditional course of succession to the throne, since he does not want Dorne to resolve into uncertainty with someone in charge who is unfit to rule because of frail health. He fears what the disease will do to him and is humble enough in his mortality to know he is not excluded from it for being king. So, he came up with a plan.
Once he reaches the third stage of the disease, high fevers, his son and heir is to end his life. This is to happen in front of witnesses, it is to be signed in blood by both the king and his heir, and if the heir does not fulfil his promise he is to be hanged for treason. Extreme measures perhaps, but all for the sake of Dorne. (Some might argue vanity and a proud man's fear to fall from great king to a drooling madman (one Mad King was enough for Westeros), but so be it.) The son agrees to this, has no choice, and continues building what he believes will be his military, his kingdom. His birthright to rule. A talented general and strategist first and foremost, but with high ambitions of expanding Dorne and with it his rule and influence.
All of this goes sideways upon the new law of succession. Suddenly the son is no longer heir to Dorne, but his older sister. An older sister who has no wish to start wars, an older sister who is not fit to be ruler in the eyes of her younger brother. But their father complies with the law and the promise taken of the son is transferred to her, the daughter thus vowing to end her father's life upon the time he chose and by it take his place.
She knows her brother will have her killed.
She knows he will not kill their father until she is dead, but she has no doubt that he will.
She knows he will have her sisters killed in order to protect himself from their wrath. These four sisters, the oldest and the three younger, are Sand Snakes.
So she has to disappear from Dorne until the time comes to fulfil her promise and take her rightful place as ruler.
Her brother will hunt her and do his best to have her killed. Her sisters will help her. One of the sisters might eventually turn out to be in it for her own gain and stab the oldest in the back (literally or figuratively).
If she does succeed and takes her father's place, her brother might not accept that. He might rebel, he might keep trying to have her killed, he might set his sights on other conquests... Or he might get killed. Who knows, endless plotting potential there. Her sisters are a whole other source of plots.
The Martells will have a sizeable army one way or the other, unaligned so far but that might change with the winds of politics as they go. Depending on what kind of plots will be tied into this one there is potential for all kinds of alliances and warfare, political or militant.
So that is where I'm at, currently xD
The king would be a GM npc preferably since he would be sick and his death a decided factor in the plot.
The brother would be open to other players to take on!
The other Sand Snakes would be open to players to take on (the younger sisters)!
I would be looking for links to get my girl, the oldest daughter, out of Dorne to stay alive (might have this in the works though)
I would be completely open to weaving this plot into plots for other houses to fill in puzzle pieces and have some writing fun!
And my girl would be portrayed by Freida Pinto :)