Treading on landmines

Recently I began running an rpg game again online. I haven't done this since August (the longest hiatus I've taken from doing 'em) and the game is intended as occult horror where weird things exist in the world but the player characters are unaware of how strange things can be, having touched the bare edges of oddness and pulled back as best they can. One of the players made an ex-teacher (Jackson)  who turned another human being (Thalia) into a thrall: she sits in a wheelchair all day when he's at work and pretty much just moves and talks to him alone.

In response to said PC I made Mary-Anne and Stanley Throckmorton living in the same building as they do. She is the girl next door, friendly and polite and probably wanting to be more than friends with Jackson, while Stanley is about 12 or so, autistic and has a bad habit of biting and hitting people. It's heavily implied Stanley breaks into Jackson's apartment some days just to watch Thalia, whom he seems to find fascinating.

He doesn't have to worry about facial cues -- for her, only Jackson is real -- and Stanley will gladly just sit and watch her for hours on end. As the player pointed out, the entire scene in-game is deeply unsettling. 'Oh, just another zombie tending my zombie. How cute.' It was an interesting and creepy scene and the player got the metaphor of it (and how, like all metaphors, the map and territory don't meet), but the whole thing got me thinking.

(Note: there IS more going on with the concept of Thalia and Stanley, but such things are spoilers for the game and the player could find this page... :))

I'd never do a scene like in any novel -- the amount of people such a crude concept of autism would needlessly offend would be staggering and while it works in response to the character the player made setting up a novel where that would come into play would be too, well, preachy in some ways and veer into after-school special territory in the end. Possibly. Somehow. I tend to apply the same rational to mental illness: such things aren't as simple as the broad strokes fiction has to use to fit them into a story.

I found it interesting that one of the things running games is, for me, is an outlet for ideas and concepts I'd never use otherwise because of that issue of landmines. So, what about you? Are there metaphors you'd never use in novels or concepts you'll never write about because it's too easy to offend with it?