The attractive specialist, Lt. Charlene Masters from 'The Alternative Factor,' and her assistant (or at least an assistant engineer) seemed to have had a 'thing' going on...
I probably wasn't, but I'll ask anyway: Was this 'relationship' followed up on in a novel, or hinted at?
No, but wasn't the Charlene Masters character supposed to have quite
a major role in that episode that was lost to hasty revisions when the script wasn't translating to screen properly? It wasn't the assistant engineer she had the scenes with.
Edit: Ah,
Memory Alpha's entry on the episode itself says: "There is no officer played by Larry Riddle as noted in the
Star Trek Concordance. Lieutenant Larry Riddle was Charlene Masters' jealous boyfriend in the first draft of the script."
See also:
http://memory-alpha.org/en/wiki/Charlene_Masters
She is briefly referred to in the Bantam novel, "World Without End".