What happens if I get the ending and then gain more reputation? Does it change the ending or is it set in stone at that point? Also I know I shouldn't look ahead because of spoilers but I saw that you can't be empress if you re involved with Eliza, but can I still get the courtesan ending?
Viewing post in Caliross, The Shapeshifter's Legacy comments
You can only see the ending once in the game. Technically you could say it's not set in stone, but unless you use the debug tool, you aren't going to watch the ending sequence again afterward.
I'd have to double check, but I think you get a variation of the courtesan ending if you are the favourite while being involved with Eliza.