I've complained about this before and I'm going to complain about it again but he sabotaged his own multiverse in the later Dark Tower books. Some of the books are real events (real in that they take place at least somewhere in the multiverse) and some books are Stephen King the Writer interpreting the Song of the Turtle. They're fictional in this already fictional construct. Insominia is an example of one of those books. It's not a story of real events that happened somewhere in reality. It's a representation cobbled together by King. It's "thin."
That's why when what's his face shows up at the end it's not the same dude we see at the end of Insomnia. The character in the Dark Tower is the real deal. The character in Insomnia is an interpretation or vision of the real person.
The reason this bothers me is that because King wussed out and tossed some of his books aside as being fictionalized in his own fucking fiction all of the connections he has included in so many of his books are less meaningful. So Insomnia connects to It, Firestarter, Tommyknockers, Pet Semetary, and a whole host of other books. What am I to even make of these connections now? There's the real events of the Dark Tower and then there's all this shit our particular version of Stephen King wrote that isn't real. He made half his own fucking books double fiction.
One stupid, lazy way out because he didn't know how to tie Insomnia together with the conclusion of the series and make it work and he set fire to three decades of his own effort to tie shit together. As an insult to his readers he introduces in one of the later Dark Tower books a secret organization that combs through is work night and day looking for references to The Dark Tower. He's clearly aping on his own fans and their love of the interconnectivety. Well asshole you fucked all that up.
I'm going to go into my fucking grave pissed off about this series.
"Stand By Me" was another Stephen King adaptation that is generally considered to be a very good movie although I have not personally seen it.
It's pretty great and well worth a watch. If you're read some of his other books like It and Dreamcatcher you're going to see some familiar King tropes though. Irredeemable bully, quirky group of child friends, Maine, etc.
If anyone hasn't seen Storm of the Century go watch Storm of the Century. I like Shawshank Redemption, Stand by Me, and Maximum Overdrive (fuck the it's awesome) a ton but Storm of the Century is just so fucking great.