Alton Lannister

Alton is the son of Cynda Lannister, from a branch of the family so far removed from the main line that his exact kinship to Lord Tywin is never established. He is a distant cousin of Jaime, Cersei, and Tyrion, though the distance shows: as a boy he serves as Jaime's squire, a memory he later calls the best day of his life, and at Willem Frey's wedding his family sits so far from the feast that he can barely see the bride.

When war breaks out between the Lannisters and the Starks, Alton fights in his house's army at the Battle of the Whispering Wood. The battle ends in disaster for the Lannisters, and Alton is taken prisoner by Robb Stark's northern army.

Held among the northern prisoners, Alton ends up sharing a cell with Jaime Lannister, who at first does not even recognise him as kin. When Robb Stark decides to send his peace terms to King's Landing — the return of his father's bones, the release of Arya and Sansa Stark, and recognition of the North's independence — he chooses Alton as his messenger.

Alton lays out the demands before the Small Council, but Queen Cersei rejects them outright. Back in King's Landing there is no free cell, so he is returned to Jaime's. When Jaime confides that he means to escape, Alton offers to help however he can.

He leans in to hear the plan whispered, and Jaime uses the closeness to strangle him. Torrhen Karstark, the guard watching the cell, dies in the same failed escape attempt.