In two separate conversations with two separate nonhuman authors from Lit, the subject of realism came up. Mainly: how much realism is needed to overcome the fantasy aspects of a story involving creatures like werewolves, vampires, demons, and djinni. All three of us seemed to agree that "as much as possible" was the right answer. For us. YMMV.
I know that I have trouble with a suspension of disbelief when the ridiculous far outweighs the plausible. Unless the entire thing is intrinsically silly, the disconnect of reality and fantasy makes a piece (movie, book, whatever) unentertaining for me. Yes, I like fantasy settings but the people should be believable as people; their actions should be logical and 'normal' for want of a better term. I also love fantasy creatures in real settings, but again, there must be an offset. The creatures can be powerful but should have some semblance of humanity or something gets lost for me.
This is probably why I never could really get into Superman. He is essentially perfect. Strong, handsome, chivalrous, innately good, honest, caring, etc etc etc... Oh, and he can't be killed or hurt. At all. It was only in later books that the writers introduced Kryptonite. His world was also fairly black and white. The good guys were generally good; the bad guys were generally really bad. There was little, if any, shade of grey (not in the 50 Shades of Grey Twilight fanfic sort of way) which made the entire thing totally unrealistic and, therefore, unentertaining for me. In Superman's defense, the story was written in a time when almost everything followed the same formula. TV shows were about perfect families, books were about perfect heroes, etc. It really only chafed when they added the supernatural element to it as that just highlighted the lack of realism and broke the already fragile veil of the story.
Maybe I'm rambling now.
In The Other Half, I tried to place my nonhuman creatures into a world as fraught with varying shades of the moral spectrum as the one in which we live. There are good guys doing bad things and thinking they're right to do so. There are bad guys doing bad things - some believe they're doing it for the 'greater good' and some because they truly enjoy being bad. There are hate groups and support groups and groups that try to cash in on both angles. There is fear and love and hatred and acceptance. There is tolerance and xenophobia. It is the world we know and see every day on our local news and that grounds the fact that the current focus isn't white vs black, straight vs gay, or religion vs atheism - it's human vs nonhuman.
In Jaisen's More Than Just a Fairy Tale, her werewolves lead normal lives. They have jobs and go to school and deal with family matters just like everyone else. The fact that they turn furry every so often is almost a side issue. I love the sheer normalcy of the setting as it makes the rest so much more believable. There is no mating bond to pull their other half to them - they date and marry and divorce. It's refreshing and normal with just enough fantasy to titillate the senses without bashing you over the head with it.
So, before I ramble even more than I already have, I'll sum it up in this way: FOR ME (notice the emphasis there, again, ymmv), the best way to ensure that a fantasy story (movie, book, tv show, etc) is wholly able to suspend my disbelief is write it in such a way that, if you removed the fantasy element from the characters, the story could stand on its own. MTJaFT succeeded in a way TOH did not. The fantasy element is too intrinsic to the basic premise for TOH to survive without it. There's a Fine Line might do better...time will tell.
Yeah, I'm totally rambling at this point but I think you get the general idea. Opinions are most welcome.