The influence was to fandom's idea of Mulder as victim. He's irrevocably damaged, his father beat him, he was psychotic when he was a child, when he profiles he goes nuts. When he profiles he vomits. When he profiles he doesn't eat or sleep, etc. I read part of it and gave up. It's way, way, way too long, there is far too much vomiting, and because its setting is pre-x-files, there is no Scully.

Here you go: http://fanlore.org/wiki/Oklahoma

On the series most of the time when Mulder is working, he's intense, he's focused, he's obsessed but he's completely functional.There is nothing in canon--except "Grotesque," which is only one episode, to support their fanon yet it was taken as gospel for a long, long time. It was a very popular story that influenced characterization in fic.