Because he was burned hard and knows the only reason he' alive is through sheer luck and his son pulling off a miracle. Near death experiences change people and Ned now knows being too honourable in the South gets him jack shit. Also don't diss his honour its the difference between men fighting in his name long after his death and men spitting on his grave as soon as he dies like Tywin.
If Stannis doesn't act like a king should and fulfill his part of the feudal contract, then there's no darkening of Ned's honor if he doesn't follow him.
See, I agree with all of this. I just want to make sure Ned does too.
[X] Plan NN
(aka CM 2.0)
-[] Prisoner exchange. All of 'em. Except:
--[] The Mountain will be executed for raping and pillaging in the Riverlands.
--[] Tywin will be sent to the wall for ordering said pillaging.
-[] You will also be given back Ice.
-[] The North and Riverlands will also receive fair compensation directly from Casterly Rock's coffers for the damage caused and men lost.
--[] And then some more, if we're to fight in Stannis' war.
-[] The Northern host will withdraw from King's Landing.
--[] If we can be neutral, to the Riverlands to wait out the Baratheon vs Lannister war.
--[] If not, we'll probably go join Stannis. *sigh*
-[] Baelish betrayed you. He was likely lying about Tyrion and had sent the catspaw assassin to kill Bran himself. Have him arrested and brought to you in chains.
--[] Tell Cersei how it was Baelish who pointed you towards Tyrion as Bran's would-be murderer and set the Starks and the Lannisters at each others' throats.
--[] (Knowing he was conspiring with the Lannisters, maybe he knows something about Jon Arryn's poisoning?) Is this to metagamey?