***MAJOR SPOILERS FOR ALAN WAKE 2 BELOW***
Having just finished Alan Wake 2 last night, my head is abuzz. Swarming with darkness, you might say. But amid the spiraling thoughts one sticking point is coalescing into a theory for me, so hear me out:
We're told over and over in the last bit of AW2 that Scratch is just Alan, Taken by the Dark Presence. It's just the same Dark Presence that was inhabiting Barbara Jagger, but now it's inhabiting Alan's body. Because of the weird non-linear nature of time in The Dark Place Alan or others could convcieably encounter TakenAlanScratch in The Dark Place at any point in time and not realize who it is, but my impression is that this isn't usually what's happening, that instead The Dark Presence is encouraging Alan's belief in a truly Other being that's trying to get him because it leads him to make decisions that benefit the Dark Presence.
(As an aside, the fact that they also call TakenCasey "Scratch" seems to just be Saga and Alan using that term to mean "a person possessed by the specific Dark Presence Entity vs a generic Taken that's controlled by but not actively inhabited by the Capital D Dark Presence. A concession to the fact that the game's audience needs to connect the two and realize its the same Entity and not Casey suddenly revealing himself to be Evil All Along or something.)
All the times Alan thinks "Scratch" is doing something it's really just him at another point in the LoopSpiral either actually possessed by the Dark Presence or just Alan being tricked into thinking himself at a different point is this separate person called Scratch (such as when he thinks Scratch burst into the Writers Room and shot him to stop his editing of Return and when he thinks Scratch is writing Return so he bursts in and shoots his other self in the head. No actual "Scratch" here, just Alan being duped.
So is Scratch an actual entity apart from Alan? It doesn't seem like AW2 supports that hypothesis. It presents pretty strongly that Scratch doesn't exist apart from Alan, that he's just Alan at a different point in the loop, possessed or not.
But then what about the end of Alan Wake 1 when Scratch is standing next to Diver Tom? Or all of Alan Wake's American Nightmare which Sam Lake has explicitly said is still fully canon? In American Nightmare, Scratch spends the whole game running around taunting Alan while he is trapped in a time loop that Scratch claims to have created and acting like a psycho. In fact, the end of American Nightmare is Alan using a film projector to destroy Scratch and escape that loop. During that boss fight "Happy Song" by Poets of the Fall is playing.
What is Thomas Zane wearing when Alan first meets him in Alan Wake 2? A tattered version of Scratch's costume from Alan Wake's American Nightmare.
What are we told over and over again Zane loved to do in his films? Play evil doppelgangers of people.
What song is playing in the first scene we meet Zane? Happy Song by Poets of the Fall.
Who does Zane now inexplicably look like? Alan and by extension Scratch.
What does Zane do in Alan Wake 2? Tell Alan where the murder sites he needs to go to to continue the loop are located, as well as feed Alan's mistaken belief that Scratch is a totally separate entity.
So...I believe that Scratch in Alan Wake's American Nightmare is Thomas Zane playing the role of Scratch to cause Alan to continue his loop of trying to "destroy" his way out of the Dark Place (what Alice alludes to in the mid credit stinger). He plays Alan's evil doppelganger specifically to push Alan further along the LoopSpiral. In Alan Wake 2, we find him "fresh off the set" so to speak, still in the clothes he was wearing in Alan Wake's American Nightmare when the film projector "destroyed" him. When questioned about his motives for helping "Scratch" later, he claims Alan had stopped writing, thereby refusing to move forward along the LoopSpiral. He had to help "Scratch" write Return because it was the only way to get Alan moving again.
Thus, for reasons we don't fully know Zane wants Alan to complete the Spiral, and in my theory he has cast himself as Scratch the Doppelganger in order to push Alan into continuing the Spiral. Then later he participated in/helped Alan write Return (potentially after Alan was possessed by the Darkness because time is all weird in the Dark Place) because he knew it would force Alan to write again and thus push him along the Spiral.
