Trias the Betrayer

Trias is a secondary antagonist in the videogame Planescape: Torment.

He's a Deva, one of the various types of angels in the cosmology of Dungeons and Dragons.

Before the events of the game, Trias was a radical towards the conflict between the forces of good and evil and he wanted the angels to make a direct action in the war between the Baatezu (devils) and the Tan'arri (demons) in order to destroy both of them. When they refused his request, Trias gathered an army of fiends to attack the upper planes in order to convince his peers that he was right.

The angels captured Trias and imprisoned him underneath the city of Curst in the prime material plane.

The Nameless One and his companions went to find Trias because he might know something about the Transcendent One, the embodiment of TNO's lost mortality. After the heroes freed him, Trias brings the city of Curst to the prison plane of Carceri to let the fiends kill the citizens because they are all corrupt in his eyes.

After the Nameless One saves the citizens of Curst, he confronts Trias in battle. After being defeated, Trias tells the Nameless One about the location of the Transcendent One in the Fortress of Regrets. The player has the option of killing Trias or explaining to him that all what he did was wrong and that he should return to the upper planes and ask the angels for forgiveness.