House Tully
Lords of Riverrun and Lords Paramount of the Trident, ruling the fertile, much-fought-over riverlands — including the feuding Blackwoods and Brackens, whom no Tully has ever fully reconciled.
The fuller tale
Ser Edmyn Tully bent the knee to Aegon the Conqueror quickly enough, and cheerfully enough, to be handed dominion over the whole quarrelsome Trident for the trouble — Lord Paramount of the Riverlands by reward rather than by ancient right, ruling from Riverrun over a patchwork of older, prouder river houses who mostly needed a referee more than they needed a new master.
Family, Duty, Honor sounds tidy on a banner and describes, in practice, an endless mediating job: nowhere is that job harder than between the Blackwoods and the Brackens, two riverlands houses whose feud runs so far back that no Tully in memory has ever fully settled it, only postponed it generation to generation.
That particular quarrel matters far beyond the riverlands in this era, because it is the feud that produced both sides of the age's deadliest rivalry — Brynden Rivers, whose mother was a Blackwood, and Aegor 'Bittersteel' Rivers, whose mother was a Bracken, each carrying an ancient local grudge into the Targaryen court and, eventually, onto opposite ends of a civil war. A Tully lord's failure to fully reconcile two squabbling vassal houses helped shape the realm's history in ways no tournament or wedding ever could.
The page and the screen
The Blackwood-Bracken lineage behind Bloodraven and Bittersteel is drawn from Martin's broader Targaryen-era history rather than dramatized directly in any Dunk and Egg novella scene, and it has not appeared on screen; Riverrun itself sits near, but outside, the Whitewalls material no season has yet adapted.