Apparently, Greg Berlanti and Marc Guggenheim wrote a movie script for a Flash movie that got scrapped after Green Lantern flopped.
This reddit
post and
blog provide summaries of the script. Together, they provide a lot of details.
There are a lot of similarities between the movie script and what we've seen so far.
Reverse Flash
The Wells character is Eoboard Thawne in the movie. There's a lot of superhero mythology that would be better read by oneself, lol, but the gist is that Eoboard and Flash are arch-enemies in a different dimension. In that dimension, Barry's parents are alive and he's happily married to Iris so Thawne who hates this goes back in time to kill his mom. However, he derives his powers from Barry and since Barry hadn't gotten his powers by then, he has to wait 15 years while building the particle accelerator. Then he'd be able to steal Barry's powers and return to his timeline. He also wants to destroy the world and make Barry's life a living hell. He wears a black suit.
Barry/Iris
Similar to the tv show, they grow up together after Barry's mom's been killed and his father imprisoned. However, both have feelings for each other but never act on them. We really haven't had a good POV of Iris's feelings so while it looks like she only sees him platonically, it's possible that there could be more. In the movie, she's engaged to a banker called Nathan Newbury. It seems this happens at the beginning of the movie and before Barry gets his powers. At the engagement party, Iris's sister Mary and Barry have the same talk he had with Joe in Episode 5 (she expected Barry to marry her sister and there's the "too slow" line).
There doesn't appear to be a major confession halfway through but Barry has a love interest called Valerie (last name Miller on reddit, Perez on the blog). She seems to be based on Bart Allen's love interest Valerie Perez. I think she's split into two characters on the show: Caitlin (with a little Cisco) and Linda Park (Wally West's love interest).
She's a scientist who plays an instrumental part in Barry become The Flash and they bond on their love of comic books - he's a Jay Garrick (first Flash) fan. Iris gets jealous when she sees them at a bar together and while they sleep together, it ultimately doesn't go very far because she can tell that he's in love with Iris.
Nathan and Iris break up after she learns that he's involved in money laundering and keeping this a secret put them in danger. Flash saves them from Cap. Cold (who's the other major villain) who attempts to kill them. He leaves a note for the paramedics on how to treat a frozen Nathan which is how Iris learns his identity (from his handwriting).
Valerie is killed by Thawne after she learns that he plans on stealing Barry's powers. I hope Linda Park doesn't share the same fate. But perhaps Caitlin learning of Wells' true motives could turn her to the dark side?
Eddie is Nathan in the sense that he's the guy Iris is serious with but he's obviously not a banker. I wonder if the Eoboard Thawne character has been split here because I don't see what purpose Eddie will serve in the story once Iris dumps him. So he must be on the TV show for an additional reason. I also don't think he will be killed off if he's Well's ancestor.
Some other similarities/twists:
Barry unravels a tornado like he did in the Weatherman arc.
Iris is a fired reporter-turned-blogger who writes about "The Guardian." She and Barry have a falling out when she refuses to stop writing about him.
RF threatens to kill Iris if he doesn't back off much like he did to Joe on the show.
While Iris loves her fiance Nathan, she also loves Barry and is his #1 supporter.
Barry also gets his power from the particle accelerator but he doesn't go into a 9-month coma.
Valerie makes Barry's suit without Thawne's knowledge and it appears that he is in the dark about what she and Barry are working on together. Barry does wake up at S.T.A.R Labs and Thawne and his scientists help him much like on the show.
Other things
Barry and Iris work together to investigate Cold. He also confides in her after her life is threatened and she encourages him to keep fighting.
While they are best friends who didn't pursue a relationship despite mutual feelings, they apparently lost their virginity to each other. LOL. Well, I seriously doubt that's the case on the show but it's possible that we might later learn that they are each other's first kiss which might have taken place due to something cliche like a game of spin-the-bottle.
RF or "Zoom" in the movie, breaks out all the inmates from Iron Heights jail. I wonder if he will do the same with the ones in S.T.A.R labs.
It seems like Barry's boss, Chyre plays more of the Joe West role. Barry was raised by the Wests but it doesn't seem like the Joe character featured prominently in the movie. Chyre is executed by Cold on live television and I hope Joe doesn't bite it the same way. Oddly enough, I expect Joe to die by the end of the season.
The movie ends as one would expect: Barry beats Thawne and destroys the particle accelerator (there's another one) and he and Iris embark on a romantic relationship.
Anyway, that's the summary of what I read. I guess now we'll have to see what else from it ends up on the TV show.