Elmo Tully

When the Dance of the Dragons split Westeros between Greens and Blacks, Lord Grover Tully, old and bedridden, had already pledged his men to Aegon II. His grandson Ser Elmo had no intention of honoring that pledge: he shut Riverrun's gates and refused to let the troops his grandfather had promised march out.

Elmo declared the whole of the Trident neutral. He would not see Riverrun exposed to dragonfire, whichever side it came from.

Everything changed when Ser Addam Velaryon arrived at Riverrun mounted on Seasmoke. Elmo mustered the riverlords and led them to the second battle of Tumbleton.

Lord Grover died shortly after the battle, and Elmo inherited Riverrun as its new lord. He did not hold it long: marching with the Blacks, he drank foul water and died forty-nine days after his grandfather. His eldest son, Ser Kermit, succeeded him.

Archmaester Gyldayn described him as a reluctant, pragmatic warrior, cut from the same cloth as his grandfather. House Tully's already undistinguished history fared no better under either of them.

And yet it was Elmo, not Grover, who ended up deciding Riverrun's course during the Dance.