I get to deal with a whole lot of crazy at work. The following rules are applicable to lots of flavors of crazy, but I've had a heavy dose of borderline personalities lately. So here are my ten rules for dealing with borderline personalities and other crazy people:

1. If you don't have to deal with a crazy person, don't.
2. You can't outsmart crazy. [Thanks to Lisa J] You also can't fix crazy. (You could outcrazy it, but that makes you crazy too.)
3. When you get in a contest of wills with a crazy person, you've already lost.
4. The crazy person doesn't have as much to lose as you.
5. Your desired outcome is to get away from the crazy person.
6. You have no idea what the crazy person's desired outcome is.
7. The crazy person sees anything you have done as justification for what she's about to do.
8. Anything nice you do for the crazy person, she will use as ammunition later.
9. The crazy person sees any outcome as vindication.
10. When you start caring what the crazy person thinks, you're joining her in her craziness.