House Fossoway follows their liege lords, House Tyrell, in pledging support to Renly Baratheon's claim to the Iron Throne. Following the death of Renly, however, the Fossoways do not follow their Tyrell overlords and instead go over to Stannis. They participate in the Battle of the Blackwater.
Sam's sister Talla tells him their father intends to marry her to Symun Fossoway.
In the books
In the A Song of Ice and Fire novels, House Fossoway of Cider Hall is commonly referred as the red-apple Fossoways, to differentiate them from the other branch of the house, the "green apple" Fossoways of New Barrel, who split from the red apples in 208 AL. After Stannis' defeat at the Battle of the Blackwater, they bend the knee to Joffrey.
Houses from the Reach