Omori Theory: Sunny is a medium. 

I can't believe you didn't mention the biggest piece of evidence: On the last day, Sunny perceives something that's largely unrelated to him. Something that he isn't supposed to know until a bit later. He sees Basil's grandma at a crossroads, fading away, BEFORE he knows she passed away when he gets to Basil's house.

this also explains why basil can see SOMETHING, more specifically sunnys interpretation of SOMETHING.

I dunno if I believe that *everything" Sunny sees is him seeing ghosts, but I do definitely agree that Mari is a ghost.

I find that many fans tend to hand wave supernatural events that happen in the game, so it’s nice to see some theories like these! Personally, I believe that SOMETHING is a mix of both paranormal and psychological. Both Sunny and Basils somethings are based on the imagery that scarred them that night. And the 3 somethings Sunny faces are manifestations of his fears, with the other somethings being intrusive thoughts that permeate around Sunny’s triggers. However I also believe that Ghost Mari does communicate through them in some fashion, this is why the somethings help Sunny calm down when fighting him, and why they say they love Sunny and ask him for forgiveness. Ghost Mari in headspace as well as during the Feat segments and the piano/Hero moment only add more fuel to the fire. I hold this same view of Stranger and the White egret orchids. While Stranger is undoubtedly a manifestation of Sunny’s view of the Basil who staged his sisters hanging (this Basil is a “stranger to Sunny). However Stranger also says things that only make sense if they are being said by Real World Basil, especially during his fight in the hikikomori route. In a way Stranger’s words are Basils thoughts following Sunny in his dreams.

It also recontextualizes the secret ending, as Mari herself passing on and finally resting, knwoing that her brother is safe, which is honestly really touching (note that Something closes its eyes before disappearing, just as someone resting will close their eyes peacefully).

also would make the stranger movers make more sense as at that point basil is dead.

Finally! I've been waiting for a theory like this for months! Thank you so much for making this! Ever since I saw that Hero also heard music from Mari, I thought I was alone in thinking that all these depictions of Mari were real. I'm glad to know that I'm not alone in thinking this. ❤️

This actually makes a lot of sense

I. LOVE THIS. You pointed out things I never thought about! I'm probably going to use this theory as reference for my Omori fan content I'm attempting to make 😊 Especially because I'm trying to do something with Spirit Mari!

To add: the Stranger's speeches bear an uncanny semblence to RW Basil's appearance and personal thoughts despite Sunny having very little interaction with him in the true route and never meeting him in the Hikikomori route. The white egret orchids we find in the grandma's bedroom and at Mari's grave are implied to be grown by Basil. Their Language of Flowers description is: My thoughts will follow you into your dreams. Now I don't think Basil is using these flowers like a 2-way walkie talkie into Sunny's brain, or that it was intentional at all. More like how a radio picks up stray signals, some of Basil's innermost thoughts about Sunny and the Incident find their way into Headspace where they manifest as a Stranger. (Get it?) Thus could also provide a Watsonian explaination for why the Truth polaroids are shot primarily from Basil's POV (with the exception of a few shots).

Psst... i see dead people.

Honestly i personally see Sunny suffering from Psychotic Depression (Major depression with psychotic features)

You should make a theory on Everhood.

Sunny is a system, as its made pretty obvious in the game, his headspace is an actual headspace, I feel like you neglected to factor this part of him as a person into your theory

First comment!! 🎉