Boros Blount
A choleric, thickset knight of the Kingsguard, more bully than hero, quick to do a cruel king's bidding.
The fuller tale
Ser Boros Blount holds the distinction of being the Kingsguard knight nobody — in either telling, on any side — bothers to defend. A thickset, jowly crownlands knight gone soft in the cloak, he is the order's lowest common denominator: brave enough at a feast, choleric with the defenseless, and reliably available when King Joffrey wants Sansa Stark beaten by men sworn to protect the innocent. The story uses him as the Kingsguard's control group — where Trant is actively vicious, Boros is merely base, a man who does shameful work not from appetite but because refusing would require qualities he has never possessed.
The books give his mediocrity a paper trail. During the Blackwater crisis he surrenders Prince Tommen to Cersei's enemies without drawing steel, and the queen strips him of his cloak for cowardice — the first knight ever expelled from the order for it — only for the family to restore him when a compliant sword proves more useful than a principled vacancy. His restored duties measure the fall precisely: by the fifth book the onetime royal protector serves as Tommen's food taster, sampling the little king's meals for poison, a knight of the Kingsguard demoted to the world's best-dressed canary and visibly aging out of even that. Jaime's audit of the White Book gives him the order's epitaph-in-progress: a man who would have been better suited to almost any other career, kept on because the institution that should have expelled him had itself stopped meaning anything.
The page and the screen
The show keeps only the function: an armored figure among Joffrey's beaters, unnamed in most viewers' memories and quietly absent after the early seasons, his duties absorbed by Trant's more legible villainy. The books keep the man — the stripped cloak, the humiliating reinstatement, the food-taster's twilight, and Jaime's withering entries on him — because the novels are conducting a study of the Kingsguard as a decaying institution and need Boros as evidence. He is alive in both tellings as far as either goes: the published books leave him tasting Tommen's suppers with poor grace, and the show simply loses track of him, the fate of every background sworn sword the camera stops needing.
Where they stand, season by season
Their fate — if death has found them, it is written here. Open at your peril.
The chronicle records no death for this soul — they are living when the tale leaves them, or their ending is a page the maesters have yet to turn.