Honestly, while I gave a long post about things I would like to see to shape a more interesting decision, the one bit of dialogue I wanted most in the finale was just the option to tell the Emperor something like "Let Orpheus speak for himself. If he refuses an alliance, I'll side with you. But if you won't even consider it, I WILL set him free." Similarly, back when he questions us about retrieving the hammer from the House of Hope, I wanted to tell him (with the knowledge I had at the time) "You can keep Orpheus prisoner until after we defeat the elder brain, but as soon as this business is done, I'm releasing him so he can challenge Vlaakith." It frustrated me to no end that so many of our own conversation choices seemed to impose the idea that it was impossible to get these two to cooperate, without even letting us push for it, even if they both ultimately reject the idea.
Exactly! Though, The Emperor does say at one point that he considers freeing Orpheus after everything is done, but then when the Netherbrain countered the plan and he had to safe us, he decided he needs Orpheus' powers for himself.
But Legit, I also thought, why not tell the Emperor to free Orpheus and let us hear him out, and if he decides to attack, we can all immediately jump him together.