From A Wiki of Ice and Fire
|Book||The Sworn Sword (appears)|
Rob, better known as Big Rob, was a simpleton in service to House Osgrey during the reign of King Aerys I Targaryen. Squinty Jeyne was his mother.
Big Rob was among the smallfolk called up by Ser Eustace Osgrey to defend his lands against House Webber. He was sent home by Ser Duncan the Tall once they realized that it would be a hopeless fight.