Brynden Tully
The Blackfish: Hoster's brother, the finest soldier House Tully ever produced, who quarreled with his lord over an unwanted marriage and never took a wife at all.
A soul of House Tully, born at Riverrun.
The fuller tale
Season One
The steadiest judgment in the Tully family, and the one Robb Stark's war can least afford to lose. With Hoster dying and Edmure impatient for a fight he is not yet ready to win, Brynden holds Riverrun's defense together by sheer experience, counsels caution the way a man does who has already seen where recklessness leads, and earns from his family the kind of trust his brash nephew has not yet learned to ask for.
Season Three
Sees his brother Hoster buried on the river with no one able to light the arrow but him, after Edmure's three failed shots turn a solemn rite into something harder to watch. He survives the Red Wedding by the thinnest of margins — out of the hall relieving himself when the doors are barred and the music turns to slaughter — and rides out of the ruin of his family's alliance alone, one of the only Tullys or Starks to leave the Twins breathing.
Season Six
Turns up alive after years unaccounted for, having retaken Riverrun with a scratch force while the rest of Westeros assumed him dead, and holds it against a Frey-Bolton siege with the same flat competence he has always brought to a losing hand. Brienne comes asking him to bring his men north to Sansa's cause; he will not abandon the castle to do it, choosing the last Tully seat over an alliance he cannot be sure will hold. When Edmure is forced to order the gates opened, Brynden refuses to leave with the surrender, and dies inside Riverrun rather than yield it walking.
How it ends for them
In the show, the siege of Riverrun ends when Jaime threatens Edmure’s infant son and sends Edmure into the castle to order its surrender as its lawful lord. The garrison obeys; the Blackfish will not. He hurries Brienne and Podrick to a boat, refuses her plea to come north to Sansa — he has a castle to die in, he says, more or less — and is cut down fighting, offscreen, sword in hand in the halls where he was born. The show grants him the death he would have picked from a catalogue.
The books stage the same siege with a different last move: when Edmure yields the castle, the Blackfish is simply not among the prisoners. He escapes by the river that named his house and disappears. As of the published books he is alive, whereabouts unknown — the rare character whose show death has no book counterpart at all, only an empty cell and a furious Frey garrison.
Their chapters, book by book
Where the page and the screen part
The two tellings split at the Twins. Show-Brynden attends the Red Wedding and survives it by stepping out to find a tree — a black joke the episode plays completely straight — while book-Brynden was never there, having stayed to hold Riverrun as Robb’s warden. The endings diverge just as sharply: the show closes his story at the fall of Riverrun, while the book siege ends with the Blackfish slipping the net entirely, swimming out beneath the Water Gate and vanishing into the riverlands. In the published books he is still at large — an unaccounted-for Tully with a sword, which several characters have cause to find worrying.
Their journey
Where the two tellings send them to the same place the road runs whole; where they part, the screen keeps the left and the books the right.