Deadly Premonition/WMG

The original Raincoat Killer was mercy killing

• It only seems fitting that someone stopped everyone from brutally killing each other. He was also probably killed by the military soldiers, even more likely by Kaysen.
  • It also made sense why he hesitated before killing his son Harry. He saw his own son driven insane by the gas, was horrified, but knew he had to put him out of his misery.
  • And why he hesitates to finish you off in the Red World. He's axe crazy, no doubt about that, but he's tempering it with Heroic Willpower.

Zach lived in Greenvale when his parents died

It looks like Zach's mother is dead in George's basement, and it also shows why Kaysen was there and how he got his mother implanted with the seeds. It never come's to York's mind because he wasn't from Greenvale

• It makes much more sense to think that it's George's mother in the basement. Harry mentions that his wife, George's mother, had the red tree implanted in her. Also, Kaysen was a traveling salesman who's been across the entire country, explaining why there have been murders related to the red seeds everywhere; the murders that York and Zach had been tracking down. He's been to a lot of places outside of Greenvale.

Zach and George are brothers, and his father is Harry

It explains why Harry lectured York the exact same way Zach's father did. Harry went through a complete name change and survived the gunshot to the head, which is why he has life support all around him. He also generally looks like Zach's father. It also explains why Zach's mother (or seemingly so) is in George's basement. George might have been sided with Kaysen for a long time, and creepily kept his mothers body as revenge after she beat him.

York isn't really an FBI agent, he's just that crazy

Seriously, if you view York as a crazy nut it could make since that he's not even a real agent. There's only one time in the game where the story makes any connections from York to the FBI and that could have been faked easy.

• Makes sense when you realize all the faults in practice York makes that a proper FBI agent wouldn't, such as York not realizing that he does in fact not have to deal with the crap the entire city gives him and yes he is entitled to all information on the murders because he's an agent of the federal government.
  • Then again, that raises the question of how he's been able to track the murders that had been occurring all over the country, and how he has all those plastic bags full of red seeds.

Everyone in Greenvale already knew "York" as "Zach"

Every time we hear Zach referred to as York, it's from York's perspective. But from the perspective of everyone else, he was just Special Agent Francis Zach Morgan. Zach/York's mind just switched the names. It would explain why everyone starts calling him Zach after the reveal, and why they all saw the real scar long before that.

• This is actually true and is hinted many times. Talking to the female owner of the Milk Barn will get Zach to say that York is together with Emily, with her replying that she doesn't know who York is. In the beginning of the game, George says that he has become the talk of the town due to his scar. York doesn't understand, as he scar is small. Zach's scar is very large though.

Willie is immortal

Kaysen says he's owned Willie as long as he can remember — given Kaysen is immortal, that's a long time. Because he's always traveling with Kaysen, he has easy access to red seeds. (George's story about the deer confirms that the red seeds work on animals). Willie acts very intelligent — for the Thomas boss fight, he tracks York all the way across town, removes his blindfold, chews through the ropes holding him to his chair, and even operates the doorknob on the door. Willie's unusual inthis could be explained by him having lived long enough to learn way more than an ordinary dog could.

• Of course, that could have been a blatant lie made up by Kaysen to keep up his act. When we see him 50 years ago as a soldier and when he drops the salesman act, Willie is nowhere to be seen.
  • Confirmed by Word of God. Willie is Kaysen's handler. He relays orders to Kaysen from their boss.

Legendary Tabatha has eaten the red seeds

Jim says that Legendary Tabatha has lived far longer than the normal 7 year life-span of a fish of her species; it is known from the graveyard deer that eating red seeds renders animals immortal. Jim also calls Legendary Tabatha a warning for mankind from nature. If she ate the seeds, then her appearance is a warning: a warning of the presence of the red seeds and their corruptive power in Greenvale. If this WMG is correct, then it transforms "Legendary Tabatha" from what it currently is (an irrelevant sidequest to catch a big fish to earn a better fishing rod) into something plot-relevant (a shining example of devilishly brilliant subtle foreshadowing for people who complete the "Legendary Tabatha" sidequest before being directly informed of the red seeds' effect on the deer in the main storyline).

The Big Bad is of the same species as BOB.

He feeds on suffering, exists in in Black Lodge/Red World. The difference being, Kaysen made the mistake of taking on someone who could exist in both worlds, by having a personality exist in each. He couldn't possess York/Zack because he's already occupied.

The Woodmans are particular suspectable to the red seeds.

Harry's dad didn't just go insane like the rest, he turned into a virtually invunerable killing machine yet kept enough sanity to attempt to track down the man responsible. Harry himself wears a gas mask at all times, likely so he's not effected by the trace amounts in the soil. And George... well.

Harry is the first Raincoat Killer.

• It's suggested that Harry is lying about something in his story, and when we play as the Rc K he's nowhere to be seen. Sure the Raincoat Killer exists in the Red World, suggesting he's dead, but then Harry appears in the White World too. Maybe the guy is capable of existing in various worlds in various forms, perhaps originally because he was trapped like Zack was.
  • So why is he pretending to be his dad? Perhaps because he's immortal, due to the red seeds. He learned about them from Kaysen, yet eventually turned on him in an attempt to atone. Kaysen expresses exasperation about 'that old man', obviously referring to Harry, and suggests that 'he should have stayed trapped too'. All things considered Harry doesn't actually look that old either, simply crippled and unhealthy.

York is...

An Angel, or similar good spirit. He takes the girls off to the forest at the end, he is totally unfazed by the supernatural (he seems more unsettled by normal people than by monsters), he’s firmly Lawful Good and Zack first met him in the White Room.

Dale Cooper. Displaced from his body by Bob, he merged with Zack in order to hunt down similar eldritch abominations. What? It certainly would explain a lot...

Some special property in Zack. Either simple Heroic Willpower, or some special supernatural defense mechanism.

An |Otherself. His replacing Zach is very similar to how Strength and Yuu switched places. York is better at manifesting than Strength was.

Possible answers to the Mind Screw entries on the main page:

• They were real; that's why nobody went outside. They were created by the runoff of the purple fumes, which made people really angry and violent. Combined with the immortality aspect of the red seeds...yeah, it's a good mix of Plebotinums to make for angry zombies. Besides, if the Raincoat Killer was real, why not the zombies? They both had origins in the same event.
• The Otherworld scenes were a reaction to York's presence in areas tainted by the seeds. Zombies sense the good guy, spring up and warp the world around him in the localized area to ensnare him and destroy him. They failed badly, though.
• She was a goddess, and as such, was granted the same power to see the zombies as York/Zach was.
• The military bit was probably not real (likely the tree hugger side of the whole tree hugger vs. logger fight we heard about from Keith's side quests, dressed up as the military), but everything else seems to gel.
• See #4 for the tree hugger part and the For the Evulz entry above.
• Yup, totally happened, just like all them zombie scenes. Zach was in control, and everything was clear for once, so the final fight could easily have been real.
• In the epilogue, talk to anyone. They have no clue who York is, and they address you as Zach. The best example is talking to Lilly, who not only greets you as Zach, but when Zach mentions that York is with Emily, Lilly not only doesn't know who York is, but half-heartedly accepts Zach's answer that he's Emily's boyfriend (because she thinks ~you~ are her boyfriend). The boys also mention seeing 'another Zach', not 'another York', with Emily. Why though? Since we were playing York the entire time, we followed the game from his perspective, even his introducing himself as York. However, the reality is that all the dialogue had a name swap between York and Zach, and when Francis Morgan rolled on up into town, he was all "FBI Special Agent Francis Zach Morgan. Please just call me Zach. That's what everyone calls me."
• All the kids we see in this game were angels (except for Mini!Zach). Best supporting info on that regarding York? When Mini!York talks to the Angel Issach and Isaiah in the Red Room at the very beginning of Chapter 24 (where all the goddesses are, plus Zach's parents), they tell York he'll be going going back to where he came from soon. He shortly ends up in the white room in the forest with the goddesses. And not to mention he's in the secret area in the white room with that Swery card, and he can be found there with Emily if you visit a second time.
• They were in the Red Room to help York out and tell him when shit was about to go down. Angel-bros for life, yo.
• If the White Room is where York is from, and where the Goddesses went after Kaysen croaked, then it must be some sort of divine limbo for benevolent and/or atoning spirits. Then that means the Red Room is obviously a hellish limbo for malevolent and/or tainted spirits, or hell itself. Makes sense if Kaysen was from there now, yes? As to why Zach was there, he was probably sent to the Red Room by Kaysen to ensure that the Morgan incident had no proper witnesses. York messed that up by saving Zach's soul and allowing it to chill out and heal up in the White Room he was from while he assumed control of Zach's broken body on the mortal plane and properly allowed it to heal, Red Room taint-free. York really is a nice guy, after all.

Forrest Kaysen is related to, or might even be the same species as Pennywise/IT

• Forrest Kaysen can change shape and assumes a human form to avoid suspicion, just like IT can change shape to whatever it's prey fears the most, and assumes the identity of Bob Gray when interacting directly with humans. Taking that in consideration, Forrest Kaysen is probably not his real name.
• Forrest Kaysen, just like IT, leaves the town he sees as his main hunting ground in peace for decades, before returning and subjecting it's citizens to torment and madness for a prolonged period of time. Keith's stories about past incidents of mass deaths related to the spiritual maps especially confirms this.
• Forrest Kaysen can influence people (George and the other red seed murderers) to do his work, like IT can make people kill on it's behalf or make them forget or ignore it's acts of violence.

The relationship between the Purple Gas and the Red Seeds, and why the military released the Purple Gas

It's made clear in the story that both have similar effects on the human psyche; it's also made clear that Forrest was responsible for spreading both the seeds, and the gas. The probable relationship between them is that the Red Seeds contain the unidentified neurotoxin and source of superpowers, the purple gas being a processed form of them-- possibly weaker, but far easier to spread. As for the release of the purple gas by the military (assuming the military actually was involved), they were obviously testing it as a chemical weapon, with the obvious use of dropping it on a hostile area, waiting for everyone to kill each other, shooting the last couple survivors, and then pretending like the whole thing never happened and moving on to the next target.

York and Zach...

...are two different real people who have a psychic connection. Which means that elsewhere there is a guy named Zach (who is possibly also an FBI Agent) who talks to an "imaginary friend" named York who helps him through his experiences as well. At some point toward the end of the game, the two will meet each other in person and their connection will be explained. Well, obviously that's not how it actually is in the game, but this was a theory my brother came up with before seeing the ending, and I thought it was interesting enough to mention here.

• Well, arguably, York is real. He's simply an extradimensional/magical entity who manifests as Zach's imaginary friend/second personality.

Willie is the Genius Loci of Greenvale

Considering that Greenvale is shaped to look like Willie on the map as well as the fact that he's also a being of the Red World, Willie might be more important to Greenvale than anyone thought.

The Red World was not pleased with the Hate Plague.

This is the reason Willie was only seen afterwards. Kaysen's actions drew way too much attention, even with the coverup, and so Willie was sent to keep him from doing anything stupid.

The Slender Man is also from the Red World, or in some other way connected to Kaysen/his dimension

Just an idea I got since some parts of the Slender Man Mythos also make heavy use of tree imagery.

Kaysen Is just a Mook, and the worst has yet to come

This is something that I came up with after reading an interview with SWERY. When he was asked what Kaysen really was, his response was "An Agent of the Red Tree, Nothing more", he also mentioned that he wasn't the only one and that there are other agents with other similar jobs. This could mean that Kaysen is really just a minor agent of sorts (he did say he was a Messenger) and that the other agents (whom ever they may be) are of higher level. They could also have their own handlers (like Willie was with Kaysen) who relay orders to them from the Red World that they come from.

• • Swery did mention he was working on a sequel...

Possible explanation for the fat men dolls on the map in the Red Room

The map in question is one of the observable objects in the Red Room in the Prologue chapter. It's a map of the United States with little upside-down peace symbols (The Mark of The Red Tree) stuck into it across various states. There's also a bunch of Kaysen dolls placed on the map, each wearing different clothing; although one of them is wearing the yellow plaid and overalls the player encounters him in later. Observing the map yields the following text:

"A doll, shaped like a fat man. It has a plate on it which reads 'Washington state"

This probably refers to the fact that the Kaysen doll in overalls is standing on Washington state (which it's safe to assume is where Greenvale is located). But what does it all mean? The Red Tree symbols could either refer to:

A) the sites of the Red Seed Murders, which York has been assigned to investigate (photos of which appear on his laptop during his drive into Greenvale).

Or B) the locations of the victims of Kaysen's tree-growing method. I'm inclined to believe that the peace symbols mark the locations of the copycat murders that Kaysen has been influencing, like George, and the Kaysen dolls mark the spots where someone's energy has been stolen by the tree growing out of their stomach- a process that would require an "agent" of the Red Tree.

As for the dolls themselves, they could all be Kaysen, or it could be that the Red Tree agents all happen to look like fat men. It makes sense that Kaysen would be assigned a whole country to himself, though, which is why he adopts the guise of a travelling salesman.

Ideas for a possible sequel

Since SWERY did say he wanted to do a sequel....

• A completely new main character. Most of the story of the first game was resolved, York's story is over, as well as many others in Greenvale.
• Centered in a new town.

Forrest Kaysen has been around far longer than everyone knows of.

His music starts out with drums, sounding similar to tribal music.