In Assassin’s Creed Rogue, Shay Patrick Cormac becomes a Templar after a crisis involving a Precursor artifact.
Shay begins the game as an Assassin working with the Colonial Brotherhood. During a mission in Lisbon, he experiences a catastrophic event after taking an Isu artifact from an ancient site. He concludes that the Assassins’ pursuit of similar relics can cause mass destruction.
Shay leaves the Brotherhood and eventually joins the Templars. The game then reverses the usual viewpoint by making a former Assassin the protagonist who hunts his former allies. Its story connects the North Atlantic, the American Northeast, and events surrounding Assassin’s Creed III and Black Flag.
Haytham Kenway is a Templar leader who becomes Shay’s ally, but he is not the character who changes allegiance. Liam O’Brien is Shay’s former Assassin companion.