The secret ending
Keep Tasi’s baby and take the canister. Make your way back to the Throne Room and evade the Empress.
However, instead of exiting via the large doorway for the good ending, go through the smaller doors off to the side.
Open the control panel and use the injector’s fluid. Activate the valve.
You’ll see the red, fleshy bits erupting all over the place. Do this for the two other panels around the Throne Room.
Note: One of the doorways might require you to place the canister to open it up.
When you’re done with all three, watch the short cutscene.