Extremophiles
The Naked Science episode on TV right now is discussing "extremophiles" and the possibility that they may live or have lived on Mars. Sometimes I think there is a human equivalent to these microbes.
For those who don't know, extremophiles is a nice logical name for microorganisms that favor difficult environmental conditions - extremes of temperature or radiation, chemical environments that would be toxic to other forms of life, that sort of gig.
Don't you know someone who lives like that in an emotional way?
I do; a friend of mine was just telling me about his regrets at having left a relationship that I'd call doomed. The person he broke up with was married to someone else, lives more than a thousand miles away, and has - shall we say - lots o' baggage, in the forms of multiple dependents and health issues.
I told him it was okay, nay, good, to make an intellect-based decision in a situation like that, but I don't think anything I said penetrated to the decisionmaking center of his brain. Or, as he'd put it, his heart. He's probably still gonna get back into that mess. See? Extremophile.
I have apparently (I hope) grown out of such behavior, though it took me years and years, and it's not like I don't occasionally relapse and be drawn to something that's not so terribly healthy for me. 
Though I think that the fact that for the past several years I've been able to eat healthy foods and only healthy foods with no difficulty whatsoever suggests that I probably have that ability in other areas of life.
At the moment, I am feeling very anti-complications, and anti-"settling." Anti-settling for less. Anti-settling down. All that.
I'd rather be airborne, thank you very much, and the concept of being tied to someone else, of having to give a good god-damn what they think of my every little decision and behavior, well let's just say it's an unsavory prospect. Apart from the sex, of course. That sounds appealing.

"Extremophiles", I like that.
Not my style, though. I'm a.....what, a moderophile?