24-year-old Lord Robb Stark was never going to win the favor of the lords of the realm. He was a wroth, deceitful, and greedy, overweight man who never forgot a slight against him. He was not particularly good with numbers or at court, and he was a terrible military commander. He also bore strong resentment for King Leo I and his father’s death.
He spurned opportunities from the king to attend feasts, tourneys, and even serve as a commander of the armies. He was plotting from day one to be a headache to the usurper and killer of his father, being a known and outspoken proponent for independence for the North. He was a petty lord who failed to maintain control of his vassals, and in the short time that he was lord of Winterfell, more than a couple had taken up arms against him and were executed.
I wish there was something of note to say about our lord of Winterfell, but if Brandon was a blemish on the family, Robb was a bloody stain. His arrogance led to an armed uprising against a numerically superior Lannister army, and he died under suspicious circumstances after three and a half years as Lord of Winterfell.
The vassals of the realm didn’t have any particular loyalty to their liege, and as soon as word got out that the inn he was staying at in the war was destroyed and he was dead, they stood down and sought peace against the Lannisters. The three-year-old Lord Torrhen II was the new Lord Paramount of the North.
King Leo showed mercy to the child and allowed him to take his hereditary role up without obstruction, beginning a long regency to await his coming of age. The vassals of the realm took complete advantage of the situation. None of them were outright against their lord, but there were many wars between lords over territories, and with the recently lowered realm authority, the Lord Paramount couldn’t legally bind his vassals to stand down, leading to many changes in local territories and a significant loss in manpower as Northmen fought Northmen in insignificant wars.
During this time, King Leo I continued what Aegon the Conqueror never finished, and pockets of independent kingdoms in the Vale were finally absorbed into the Iron Throne’s realm after six decades of independence. The North didn’t commit forces to these wars with so much petty infighting amongst them, though they did officially swear for Leo in the wars, gaining his favor.