What is the name of the protagonist who betrays the Assassins in Assassin's Creed Rogue?

Shay Patrick Cormac is the Assassin's Creed Rogue protagonist who turns against the Assassins.

At the beginning of Rogue, Shay serves the Assassin Brotherhood and works with Achilles Davenport. After witnessing the devastating consequences of an attempt to recover a precursor artifact, Shay rejects the Brotherhood's methods and becomes convinced that the Templars can prevent similar disasters. His change of allegiance drives the rest of the story.

Shay's betrayal is not simply a change in costume or faction. The game presents his former allies as opponents and gives him Templar resources, including a modified Assassin outfit, new weapons, and access to Templar intelligence. This reversal was a major narrative distinction for the franchise.

The character is not Charles Lee or Haytham Kenway, both of whom are Templars associated with other games. Shay's story takes place before the events of Assassin's Creed III and overlaps with the era of Black Flag.