The Dancing master told us all, that when faced with death, there's only one thing you better ever tell him: "Not today!"
Ned was an idiot. He was speaking of Stanus becoming King even though he admitted Soldiers don't make great kings to Roberts brother.
Joffrey isn't a Baratheon, he's a Lanister, so it should have been obvious the little brat was going to do what a brat does. But even his mother knows that without the north, they can't fight Stanus and they For Damn sure can't fight the Dothraki. That is why she said NOOOOO! They are trapped honestly. They Lanisters have 3 different Armies coming for them and only half an Army with Jamie now captured. Dude took 10 soldiers out by himself before they got him down. He may be a prick sometimes, but he never fails to handle business when he pulls that sword out. he also never fails his brother. In a weird way I kind of like Jamie, because he's dirty, but everything he does is still in loyalty to his family.
Rob proved he might not be the warrior his father is by avoiding Jamies sword, but he's a hell of a lot smarter. I haven't read the books, but you can see pretty clearly that John is the real Leader in the family.