May I ask you a question? How hard is it to write a script based on book based story? We've seen novelizations of the movies and some episodes, but this is backwards. AM I making sense? Pretty much the dialogue and the scenes have already been written in the short story. So how can, for example, one script for Mind Sifter be any different than another? (And no this has nothing to do with the discussion up thread. This is a technical question.)
I can answer that question to begin with. (Also, Gerrold told me that that Rick and David Reddish didn't even read the fanzine story so they actually only "wrote a script based on a book". They didn't consider the original fanzine story at all.). I find it easy - and more of a "school assignment" than just writing out of pure creativity. The first thing I did was to write the teaser - because that sets up the entire tone of the episode. Then I broke up the original story into "scenes" as if they were a script.
Then comes the "work".... figuring out how to arrange them to tell the story in a "TOS style", how to keep the audience engaged, and deciding what the story is that the original author is trying to tell. After that I work on "flushing out" the original story and deciding if anything should be added to make it compelling. (sometimes this is a b or c storyline, or adding details to the original.)
This is the step where the "differences" would come in. Whatever "flushing out" or actual new material is added makes the differences. For instance, one of my "flushing out" came from discussions with Shirley back when she published the original. The idea that Chekov was beaming down into heavily McCarthy-era-red-scare-America never occurred to her. (she issued a four letter word when I pointed it out). So when I wrote it this idea figured into it.
Part of the equation is deciding what to see and what not to see. A "story" focuses on TELLING you a story, while a film SHOWS you the story. One of the changes I made was to show Kirk getting tortured.
All of the above, especially choices, leads to both similarities and differences. For instance, it's unlikely that another writer would add the "Red Scare" issues I did (partly for Shirley and partly to honor Walter Koenig), or the other nods to Koenig I put in (because it was a "Chekov story"), but it's altogether possible that another writer would have chosen to show Kirk getting tortured or added the realities of the 1950s institutions that I knew from my LICSW background (and which I added partly to honor John Carrigan's father). Two writers can very well come up with ideas that similar. The "execution" of the idea is what makes it different.
Does that start to explain it?
Just another added note...since Rick, David and David based their script on the original story, Chekov probably doesn't even appear in the episode, rather than being one of the primary characters.