For Lawrence, 35, a real-estate investor from New Jersey, it was Hannah. Hannah (her name has been changed) was a publicist in New York City—tall, model-thin, with a bad eBay habit when it came to mod vintage dresses and a near-fanatic obsession with Friedrich Nietzsche and Britney Spears, in equal parts. She was stunning and brilliant.

She also had a dark side.

Hannah was paranoid—convinced that strangers were plotting her demise—and a chronic liar obsessed with men in positions of authority. She was also prone to random fits of crying. Lawrence remembers pulling into the parking lot of a CVS to buy a toothbrush one day. He returned to find her in his car with the radio set to maximum volume, blasting My Chemical Romance and sobbing in great, heaving spasms for no particular reason. None of this made Lawrence think that he should be investigating easier romantic prospects. On the contrary, he was hooked.

"It was the sort of thing where you see this wounded bird and you just want to constantly repair it," Lawrence says. "You never knew when she was going to cry and when she was going to perceive somebody to be after her. It was like the Stockholm syndrome—you become sympathetic toward your captor instead of realizing Oh my God—I'm a hostage!'"

You've dated a woman like this. In all likelihood, your friends sounded alarms that you willfully ignored. Your parents pleaded with you. Looking back, you realize that even you knew it could only end badly. She's the Crazy Girl—the one who made everyone wonder about your sanity and fear for your future. She may have taken the form of the smoky-eyed goth brooder, the tortured heiress, or the unhinged sorority girl. Whatever her identity, chances are she was intoxicatingly sexy, intense, unstable, mercurial, and impossible to be at ease around in social settings. She was completely and debilitatingly exhausting. So why the hell was she so compelling? And why are you still thinking about her?

"I think whenever you're taken by someone, be it male or female, who has the potential to lose themselves or to transform in front of you, there's something very attractive to that," says actress Parker Posey, who's played her share of Crazy Girls onscreen (Nora Wilder in Broken English, "Jackie-O" Pascal in The House of Yes, and the title role in Fay Grim, to name a few). "It has the ability to transform you. Because someone has just thrown the marbles on the floor and you don't know when they're going to do it again. It's not a relationship based on trust."

Of course it isn't about trust. This is about lawlessness. Chaos. Escapism and unpredictability—a balls-out, soul-affirming what's-nextness that is so rare and so powerful that you completely forget to give a shit about consequences and personal sacrifices. That kind of relationship has the potential, as Posey says, "to take you down roads." And whether you're the kind of guy who drives a Prius or the kind who drives a chopped-out vintage Harley, at some point, you can't help taking that ride.