You need the Emperor alive, as he’s actually the only one who’s preventing you from being completely corrupted by the Absolute. If you fight him, you’ll go up against his Intellect Devourer brain creatures, as well as the Githyanki invaders.

Is it better to side with the Emperor or Orpheus?

Freeing Orpheus may result in the party becoming mind flayers, while siding with the Emperor can mean losing a character.

Should you trust the emperor?

Though your choice to trust the Emperor is completely up to you as a player and your character’s morals, if you’re wondering if the Emperor is the “good guy,” we can safely say, by definition of his actions, that he is not.