I don't want to go overboard with this, but I've been thinking that the way I feel about my closest friends may be more like the way most people feel about their families than the way most people feel about their friends.
The distinctive factor that seems to set apart one's family from the rest of the world is that one can't choose one's family. Now, if this just meant that one can't select one's family from a list, it would be uninteresting—one can't select who has a social security number that's a permutation of one's, either. My point is that even though one can't choose one's family, one still has a strong motivation to deal with them. Even if one has been estranged from one's sister for thirty years, one still feels an ongoing reason to get back in touch—“because hey, man, she's your sister&rdquo. I used to find this disturbing and fight it, but now I recognize it as a basic fact of human psychology, and the occasional occurrence of a family that's happily estranged and would never consider contacting one another again doesn't affect its truth—I'm not claiming it's a law, only a rule. If I had to guess, I'd say that it's due to some low-level biological wiring that overrides reason, but I'm no psychologist, so take that as just a pet theory.
Anyway, one can't choose one's family, and this seems to give one a mysterious power over other people—the power to permanently reject them. The thing is, for my close friends—Ed, Charlie, Laura, Ratha (listed in order of my meeting them)—I simply can't conceive of what this rejection would mean. These are all flawed people (I think all of them would admit that, and of course I'm not claiming freedom from flaws myself), and with Charlie and Ratha especially I've had some very unpleasant interactions, but even then the thought of “rejecting” them appeared not just a bad idea but actually almost incoherent.
I still haven't come up with any objective criteria for what people qualify for this group (and certainly any objective criteria for future admittances would be irrelevant—I have what seems to be an almost 100% accurate intuitive evaluation of whether someone is “my kind of person”, but I can't formalize it). But, hey, they're my family. (Along with some members of my biological family, of course.)