Imagine the modern society, except all dead people spawned ghosts upon death.
The ghost of the dead inherits memory and personality of its past living self, appear as translucent wraiths that can partially interact with the material world by blowing objects about as though a gust of wind.
The ghosts have to consume "ghost-juice" or Ectoplasm to survive (as a ghost), they do this either by attacking and disintegrating another ghost then feasting upon its remains, or by absorbing the "soul" of a living human being.
When a living human being's soul is consumed, nothing really harmful happens, except when a human with a weakened soul dies, the ghost that spawns from that person will be weak and may straight-up disintegrate upon "birth". (Souls are generated steadily by a living human being from infancy, and small losses can be recovered, but an ordinary person cannot generate more than 2 or 3 "ghost-worthy" amounts of Ectoplasm, while a ghost needs to consume an amount of Ectoplasm equal to itself every 50 years or so to stay healthy. Consuming more will make it stronger proportional to the amount of extra consumption.)
Now, assuming no method of artificially creating Ectoplasm is available, will the human race become hostile towards the ghosts? (Manifested by researching methods to eliminate them) If so, why? Since the only reason a still-living person can be hostile towards ghosts is because the person wants to be a strong, healthy ghost themselves after death, which makes their loyalty to humanity necessarily short-lived. Also, would it be reasonable to expect that some rich or powerful people will continue their existences as ghosts after death and hire/coerce a bunch of humans to regularly "donate" their souls to them? Or would becoming a ghost automatically invalidate a person's status as a ruler? Can humans and ghosts eventually work out a sustainable situation?
- There are no ghosts belonging people who had died before the year of 2016, that was the original idea.
- "Strength" describes mostly a ghost's ability to kill other ghosts.
- Ghosts can "die" from attack by other ghosts, Ectoplasm-starvation or mental degeneration, all of which leads to it exploding into a cloud of Ectoplasm.
- Ghosts can easily communicate with living human by whispering or doing sign-language (they can't speak loudly due to limited interaction with air.) Supposedly, stronger ghosts will be larger and "denser", allowing greater, though never as complete interaction with ordinary objects as compared to real human.