Ryger Rivers is a bastard son of Lord Walder Frey. After the War of the Five Kings, he joined the Base Sons.
Ryger is one of Lord Walder's many bastards. His mother was a peasant girl who milked goats. When he was born, his mother brought him to his father. His mother was granted a plot of land so she could help Ryger. When he was older, he was brought to the Twins, to live with his trueborn and baseborn siblings, learning to read and write, though he was never a natural fighter and was far less talented with a sword than his brothers Stevron, Walvar and Walder were.
When Catelyn Tully arrived at the Twins to discuss terms with Walder Frey to allow Robb Stark and his army through, Ryger was present at the meeting. Walder was being rude to Lady Catelyn during the meeting, and Ryger attempted to chastise his father for his discourtesy. But instead Ryger is chastised by his father, being reminded that he is his bastard by a milk maid.