wherein rhaegar wins the war, and jaime manages to keep his head by taking a stark for a wife; or five times jaime lannister braved his marriage and the one time he was brave for its sake

When Dorne became one of the Seven Kingdoms, they agreed to replace the Westeros Law of Inheritance with the Dornish Law, so that the same laws would be followed throughout the realm. Or, Five times there was no male primogeniture in Westeros, and this wasn't as helpful as you might expect.

Five lives Arya Stark had with Gendry Waters, and the one that she didn't. Or, (This is how she meets a man with a mop of black hair and eyes the colour of the seas who is quiet and strong and tall where she is loud and brash and small.)

If you want a happy ending, that depends, of course, on where you stop your story.

“I happen to think that I would like to see you in my bed. I’m also not in the habit of forcing people into it. If you wish to leave, the door is right behind you. I will also inform you that no one who was in my bed ever regretted it.” Or: where Oberyn seduces the hell out of Jaime.