A few insites from a Black Isle Staff member:
"...what should I mention first? How about interaction
There are just so many interesting people (or creatures)
to meet in the game.
For example: there's this girl running around the Hive
and, if you follow her, you can see that every time she
gets near a door, she turns and runs away. If you talk
to her about it, you find out that's she's deathly afraid
in 'da bar.'
in the Mortuary.
See, in Planescape, any enclosed structure, whether a
door-frame, a crate, even a mug of brew could be a portal
to another dimension! She apparently, got sucked through
a portal once and had a somewhat unpleasant experience,
as you can see by the fact that she's missing body parts!
Throughout your conversation with her, you constantly
hear her teeth chattering. You figure she's just scared,
but on closer examination, you notice that her teeth are
actually moving independently of her mouth! Creepy! "
- Scampy Art Guy , at www.planescape-torment.com