You absolutely have a point about that, Nivm, and should keep it in mind for future reference.
I also feel fairly strongly about the concept of promising, and while you make a good statement on the general idea of an author-reader relationship, I don't want anyone to get the idea that I
necessarily promise anything.
Read free, but read at your own risk.
I also wouldn't normally do too much revealing, but I'm still indulging in world-building, so some exposition might be useful:
The Spirits are a bit beyond the cycle of life, themselves. They're immortal, and immaterial, and don't breed in the same way as truly living beings do. You can think of them as guardians of the cycle of life, but they definitely hold and use the keys to that cycle, and they can and do go beyond the limits of that cycle to serve what they consider to be their "higher purposes".
Also, they're not the same thing as gods: They're not tied to any cause, idea, or justice system not their own, and of their own making and policing, and they don't have a morality that we would entirely recognise, let alone entirely recognise as "good". They hate undeath and stagnation, but they have an agenda--and sometimes a Spirit will have an agenda that's unique to itself--and they don't necessarily mind bending and warping the life cycle, to suit their purposes. They just don't want to see it broken.
I wouldn't get the idea that they're not very altruistic beings...certainly, they're some of the most influential "good guys" of this world, for some certain, and important, values of "good", but you also shouldn't get the idea that a Spirit wouldn't do something that you and I, as living, sentient, moral beings, wouldn't understand, agree with, see the point of, etc. They're alien and Other, and they could and would, very easily, turn you into something alien and Other, without any prior consultation, or strong possibility of reprisal, and then use you for the same purpose, and with the same consideration, you would use a crowbar.
They have a concept of friendship and cooperation. They apply that concept to other Spirits, and possibly a few other beings of a comparable order, but not to props.
And not typically to gods, either, whom they mostly still consider to be "tools", if of another definition...
Also, while this singular bat-woman won't die of "natural" causes, she's very much not undead, and could still die from a great many of the things that would kill another living being, depending on the living being you have in mind.
As for further speculation: Feel free, but this is only part 1, and please be advised: I
will freely steal any ideas you present here, and then turn them into something alien and Other, again without prior consultation, or strong possibility of reprisal.
Such is the nature of this thread.