when roose bolton betray robb stark and start aliies with tywwin

Roose Bolton betrays Robb Stark at the Red Wedding , which happens near the end of A Storm of Swords and in Season 3 of Game of Thrones. He aligns with Tywin Lannister’s side before the massacre, after Robb’s position weakens and the Freys turn against him.

What happened

• Roose had already been quietly playing both sides.
• The open betrayal comes when he joins the Freys and Lannisters in the trap at the Twins.
• During the Red Wedding, Roose kills Robb personally in the TV version.

Why it happened

• Robb lost key political support after breaking his pact with House Frey.
• Tywin’s side offered Roose a better path to power and survival once the Starks started losing ground.
• Roose is portrayed as cold, pragmatic, and willing to switch sides when it benefits him.

In plain language

Roose does not suddenly flip in one moment; he slowly shifts allegiance as Robb’s cause falls apart, then seals the betrayal at the Red Wedding.