From A Wiki of Ice and Fire
Ser Robert Strong by Robert O'Leary
|Book(s)||A Dance with Dragons (Appears)|
Ser Robert never shows his face, hiding it constantly under his greathelm. He apparently has no physiological necessities, consuming neither food nor drink.
According to Qyburn, Ser Robert made a vow of silence, supposedly one of not speaking until "all of (King Tommen's) enemies are dead and evil has been driven from the realm."
He is eight feet tall, with legs as thick as trees, a chest worthy of a plow horse, and shoulders that would not disgrace an ox. His armor is steel plate enameled white, over gilded mail. A greathelm hides his face, with seven silken plums in the rainbow colors of the Faith streaming from the crest. A pair of golden seven-pointed stars clasp his white cloak to his shoulders.
A Dance with Dragons
Before her walk of shame, Queen Cersei sends word to Qyburn to replace the empty spot on the Kingsguard with one that would serve as her champion in a trial by combat. When Queen Cersei arrives at the Red Keep after walking naked from the Great Sept of Baelor, Ser Robert Strong lifts her up, carrying her to the gatehouse, and is then introduced as her champion by Qyburn.
In the epilogue, Kevan Lannister remembers that Meryn Trant claimed that Ser Robert took neither food nor water, and Boros Blount said he had never seen him use the privy. Kevan has inexplicit suspicions about the identity of the man, suspicions he believes are shared by Mace Tyrell and Randyll Tarly. Kevan makes clear to the small council, however, that it is in everyone's best interests that Strong's identity not be questioned and that he must prevail in Cersei's trial. If Strong failed and Cersei was found guilty, Tommen's legitimacy as King and Margaery Tyrell's as Queen would be thrown into question, hurting both the Lannisters and the Tyrells.
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