On "House of the Dragon," the prominent Lannisters at court are a pair of twin brothers: Lord Jason Lannister and his brother, Ser Tyland Lannister. Jason, the elder twin, is the Lord of Casterly Rock, seat of the Lannister family. When he's introduced on "House of the Dragon," he's first seen smugly (and unsubtly) trying to convince Rhaenyra to marry him. Rhaenyra is unimpressed and rejects him, frustrating both Jason and her father, Viserys, who's hoping to make her a match sooner rather than later.
We see less of Jason's younger twin, Tyland, who seems to be on the king's advisory council and takes messages back and forth from time to time. If "House of the Dragon" follows a similar storyline as the book "Fire & Blood," both twins will have a significant role to play in the Dance of the Dragons.
