It seemed to me that someone must have put Joffrey up to
beheading Ned Stark.
After the trial all someone would have had to do is ask Joffrey who advised him to that and they would have known who was pulling strings behind them in a way that is against their plans. The obvious guess is Littlefinger, but you can't think he's dumb enough to think Catelyn wouldn't ever find out.
Does anyone know why Joffrey did that when everyone around him had another plan and thought he was aligned with it.
Littlefinger's plot
Littlefinger plotted to get Ned Stark to King's Landing, as explained in A Storm Of Swords ...
Petyr made Lysa Arryn write the letter, which forced Ned to investigate Jon Arryns death.
Then he used Ned's overly faithful character to turn him against the Lannisters by telling him their little secret. Finally he made sure that the Gold Cloaks would be ready to take him into custody.
Therefore it's mainly Littlefinger's guilt, but there is no evidence (yet), that he actively manipulated Joffrey.
At this time war already begun, Robb Stark was marching south and Jaime Lannister was taken captive, thus starting war couldn't be a reason. Besides that Joffrey was known to be cruel and volatile and didn't need much reason ...
to kill someone as he proved many times.
What about the conversation between Tyrion and Varys?
“Who truly killed Eddard Sark, do you think? Joffrey, who gave the command? Ser Ilyn Payne, who swung the sword? Or… another?”
...
Tyrion cocked his head sideways. “Did you mean to answer your damned riddle, or only to make my head ache worse?”
Varys smiled. “Here, then. Power resides where men believe it resides. No more and no less… A shadow on the wall, yet shadows can kill. And ofttimes a very small man can cast a very large shadow.”
Varys loves philosophical discussion like this one. He's telling that Ned Stark wasn't killed by a single man. Joffrey gave the command, Ilyn Payne executed it, but this all was only possible because most people believe that a king has power. Without that belief soldiers would put down their swords and Joffrey would just be a little kid.
The "small man" he refers to was probably meant to be multiple people. For one Joffrey is only a boy, therefore he's the most likely subject. But as he's talking to "the Imp" it could also be meant to motivate Tyrion.
Interpreting this conversation as proof that Littlefinger put Joffrey up to it, is very far-fetched.
Conclusion
Probably Joffrey just did it out of the blue clear sky.
This has not been confirmed by Mr. Martin and is therefore speculation. Assuming of course that Joffery is not just a twisted little shit, then the following are conversations in the book between Tyrion and Varys that may shed some light:
“It does seem my sister was telling the truth about Stark’s death. We have my nephew to thank for that madness.”
“King Joffrey gave the command. Janos Slynt and Ser Ilyn Payne carried it out, swiftly, without hesitation…”
“Almost as if they had expected it.”
Then later on:
“Who truly killed Eddard Sark, do you think? Joffrey, who gave the command? Ser Ilyn Payne, who swung the sword? Or… another?”
Tyrion cocked his head sideways. “Did you mean to answer your damned riddle, or only to make my head ache worse?”
Varys smiled. “Here, then. Power resides where men believe it resides. No more and no less… A shadow on the wall, yet shadows can kill. And ofttimes a very small man can cast a very large shadow.”
Littlefinger is implied to be the "small man" here. Littlefinger is also the only person with a lot to gain from this chaos. Revenge, continued war, the isolation of Sansa...
It seemed to me that someone must have put Joffrey up to ...
I see no substance for this suspicion.
I think it would be a mistake to look further -- it would be looking for something that is not there.
It appears to be a spontaneous decision by Joffery. And it is entirely consistent with his character.
He is sadistic and greedy for power.
The moment he catches a whiff, he springs into action. He has his eye on the ball, and will seize any opportunity to cause pain. You can see this time and again, in his every movement. The first example is with the butcher's boy. Straightaway he sees he has the upper hand. He is in a position of power, and he works it -- exploits the situation to leverage maximum suffering.
In this case, he is expected to make some formal speech just to confirm what grand-meister Pycelle has stated. Suddenly he has the stage. With the crown on his head in the crowd at his feet, he realises "I am the King! I can do whatever I want. In this moment, there is nobody to stop me!"
To his own mind it must be a giddy stroke of genius. An act that simultaneously produces the delicious cruelty of breaking his bride's heart, and establishes his power by directly flouting his family and advisors in public.
This is his crowning moment. He is blazing with his own power and glory.
This is clearly not the action of a man under the thumb of another man.
Pycelle. Little finger was close to achieving highest rank attainable, that of Hand, the fruition of plans, having Ned killed threw that into the bin. Pycelle on seeing his influence wane might have tried a lil influencing of his own in a bold move, he was always one to put Lannister above all conduiting for acts of brutality. Then there is his constant restamping of the 'traitors blood.'
For me, it's crystal clear what happened, and I thought this early on though it took a while for it all to come into place. No doubt Littlefinger put Joffrey up to it, Ned would have sent a raven to Catelyn and it would all have been over for Littlefinger, therefore he had to go once he decided to betray Ned. But there's no way he'd let himself be implicated directly, therefore he cut a deal with Janos Slynt. It was Slynt who convinced Joffrey what to do (on LFs suggestion/manipulation), and it was Slynt who had Payne ready to go to slice and dice before anybody could put a stop to it. I still think this is the reason Littlefinger is going to eventually pay.. Maybe Sansa will find out from Bran and do in LF.
