Write about a medicine cat who receives a prophecy or an omen about the deputy of their Clan, showing that deputy to be a power-hungry, aggressive cat. The leader dies in the medicine cat takes the deputy to the Moonpool to receive their nine lives. The medicine cat has a choice to either kill the deputy and return to the Clan, saying that the deputy died on the journey, or to allow the deputy to become leader of the Clan and face the consequences. What does the medicine cat choose?

I really like this one. It's been sitting in my notes for ages and I planned to use it for a fic one day. I still might!