Is there any original fiction with the animated series crew? I'm thinking of novels with M'Ress and Arex in particular.
Two thirds of "Star Trek Log Seven", "Eight", "Nine" and "Ten" each contain all-new material, with several featuring backstories: with another Edoan (not Arex), a story with M'Ress and three other Caitians going rogue on the ship; plus M'Ress masquerading as a male Kzin when a junior officer on a mission.
Both characters were in the post-ST IV DC Comics, then vanish by ST V. It is later revealed that they time jump in the "Gateways" saga "New Frontier" novel instalment. They later move over to the USS Trident and also appear together in a NF comic mini-series. Arex moves to security, which was Peter David's original intention (and given to Ensign Fouton) for his post-ST V comics. M'Ress had to be reconceived as an antelope woman, M'yra, in that series, but still a love interest for Sulu.
Ensign Janos, the Mugato, shares some interesting scenes with M'Ress in NF and it is revealed that he has some Caitian DNA in his artificially-created genetic structure.
IDW's "Year Four" and the current "Year Five" TOS mini-series have featured Arex and M'Ress. DC Fontana gave Arex some telepathic attributes that were meant to have been revealed in TAS, had it continued.
The Star Trek Logs were OK, but I'm still a bit flummoxed by the author gratuitously adding subplots involving the Klingons even when the original episodes didn't involve them at all.
Kirk's old Klingon Exchange Program room mate, Kumara, was from an unused two-part TOS spec script that ADF wrote, anticipating a Season Four. When he was given little warning about expanding only one episode for "Star Trek Log Seven", he pulled the script out of his filing cabinet and cannibalised it. Kumara also returns in another Log.
I think it's a shame that these characters haven't been explored in a TOS context, especially M'Ress. Do the Caitians as a species appear in any novels?
The obvious one that could have included M'Ress was "Uhura's Song", which featured a felinoid medical mystery, but the late Janet Kagan had never followed TAS.
There have been quite a few individual Caitians in the novels, but I don't remember anything that focused on their homeworld and culture, if that's what you mean.
A little on culture in Shane Johnson's "Worlds of the Federation".
I've also just found that M'Ress appears in Galactic Whirlpool. I'm going to check them out, many thanks.
With Arex.