The red priest squatted down beside her. "My lady," he said, "the Lord granted me a view of Riverrun. An island in a sea of fire, it seemed. The flames were leaping lions with long crimson claws. And how they roared! A sea of Lannisters, my lady. Riverrun will soon come under attack."
Thoros sees the siege of Riverrun in the name of the Lannisters (and the King on the Iron Throne) which will follow the Red Wedding.