What exactly ARE haunts?

[Yqatuba]

The book says they are deliberately a combination of trap and monster. I figure most haunts aren't actually the creature's souls but are more like an "echo" left behind when a bunch of people die horribly.

[Pan, definitely not a Kitsune]

Pretty much, yeah, though it doesn't necessarily need "horrible death". Anything with strong enough emotional resonance will suffice.

Also, I'm pretty sure it says somewhere that the same person can become a ghost and leave behind haunts, but I'm not sure.

[blahpers]

"Echo" is a good word for it--they're essentially psychic impressions left behind after sufficiently traumatic experiences. The spirit of the haunt's originator may have passed on already, may be a ghost or other undead elsewhere, or might even still be alive.

[Tim Emrick]

Here's the relevant text from the GameMastery Guide:

d20pfsrd.com wrote:

The distinction between a trap and an undead creature blurs when you introduce a haunt—a hazardous region created by unquiet spirits that react violently to the presence of the living. The exact conditions that cause a haunt to manifest vary from case to case—but haunts always arise from a source of terrific mental or physical anguish endured by living, tormented creatures. A single, source of suffering can create multiple haunts, or multiple sources could consolidate into a single haunt. The relative power of the source has little bearing on the strength of the resulting haunt—it’s the magnitude of the suffering or despair that created the haunt that decides its power. Often, undead inhabit regions infested with haunts—it’s even possible for a person who dies to rise as a ghost (or other undead) and trigger the creation of numerous haunts. A haunt infuses a specific area, and often multiple haunted areas exist within a single structure. The classic haunted house isn’t a single haunt, but usually a dozen or more haunted areas spread throughout the structure.

My interpretation is that a haunt is powerful psychic or spiritual impression (or "echo") left by a traumatic event. It has some of the characteristics of an undead creature, but lacks the substance, identity, will, or whatever to be a creature in its own right. Sometimes, the haunt has a limited ability to communicate with the living, but that's usually more like a broken record of the original victims' anguish than any kind of true dialogue.

This sort of "psychic echo" to frequently used by real-word paranormal researchers to explain things like cold spots, poltergeist activity, and the sort of apparitions that are always seen repeating certain actions but that can't really interact with the living.

Just last night I ran a PFS scenario involving a number of haunts, with very flavorful--and nasty!--examples designed to both pose a serious threat to the PCs and to reveal the dire history of the place. Which, to be honest, is the best way to use haunts.

Spoiler:

In "The Haunting of Hinojai," the main villain committed many forms of ritual torture and murder that produced haunts throughout the site. In at least one case, they also reanimated their victim as an undead monster under their control. It's a fun adventure, but VERY dangerous if the PCs aren't prepared for this kind of threat! It only took one whammy for the whole table to go more paranoid than a thief who searches for traps every five feet.

[Cole Deschain]

My snarky answer?

Haunts are ghosts done right in a mechanical sense.

[Darigaaz the Igniter]

Traps that are bypassed with channel energy instead of disable device.