Ser Cleos Frey is the eldest son of Lord Emmon Frey and Genna Lannister. He is an anointed knight. Cleos fights in the War of the Five Kings, but is killed by outlaws between Duskendale and Maidenpool.
A Clash of Kings Edit
Cleos was captured at the Battle of the Whispering Wood alongside his cousin, Jaime Lannister. He is dispatched to King's Landing by Robb Stark to present the Stark peace terms. He returns with a counter offer, but is arrested again after some of his men try to free Jaime Lannister, which was a ruse concocted by Tyrion Lannister.
A Storm of Swords Edit
The group is ambushed on the road between Duskendale and Maidenpool, and Ser Cleos is shot with arrows through his right arm and chest. When his horse freaks, Cleos foot gets caught in the stirrup and drags him along the ground, killing him.
Aftermath of DeathEdit
Jaime Lannister takes Cleos' sword and uses it to fight Brienne, shortly after Cleos' death.
In A Feast for Crows both Jaime and Brienne think of Cleos. Jaime doesn't mourn him, but he does tell Emmon and Genna about the manner of their sons death, whilst Brienne thinks about Cleos whilst travelling between Duskendale and Maidenpool.