I just finished my first playthrough - as Fane. In the ending sequence, I talked to that Eternal voidling (not that it’s possible not to talk to her) about the possibility of the return of the Eternals. There was no choice in that dialogue, but it ended by her telling me that I must choose (implied later) between the return of the Eternals and the freedom of the mortal races.
Now after the last fight, when I sat on the throne, I received 4 options:
- Assume the divinity
- Release the source
- Purge the world
- (Fane) Return of the God King
I clicked on the first one (not the return of the God King), yet I still received the ending where the Eternals have returned and enslaved the mortal races.
I believe this to be a bug (as there used to be a different and much more positive ending, according to people who have played as Fane in the past) - and a pretty sad one, since it has ruined the experience for otherwise exceptionally good game.