Whoever they are, I don't plan to kill them, no. That would be pretty fucking counterproductive, because they are the only person who is aware of every possible way to end the game! I'm sure you can understand why that information is valuable.

As for the volcano spirit, I plan to ask it myself if there are other ways to end the game. If it refuses or there simply aren't any, I am going to kill it. In fact, I might just kill it anyway.