I understand and love that this system is fiction-first! But a question about the lore of ghost possession: Roughly how much life essence does a normal human have? Ghost characters must possess and feed on life essence to reduce stress, and I assume to continue existing. But can a ghost drain essence more than once from a person? I ask because a player in our game is a Whisper who wants to go Path of Echoes and be a Ghost character. We wanted to hear from the brilliant minds behind the world before deciding for our game. Thanks and please keep doing more! We can't get enough!
I think that's one of those things that each game defines on it's own.
Technically speaking, a PC's health is measured by stress and trauma. An NPC is weirder and pretty much left to narrative and the GM's discretion.
So it'd be your downtime engagement roll, and depending on whether the PC just wants energy, or to kill the NPC, that would define your measurements of what is a successful roll, a limited success, and a failure.
Pretty much like determining how much damage you do in combat.
Yep, it's a thing to customize for your group.