I'm no expert on this, but here is how I saw it in my situation. When the psychopath met me, she did the whole victim routine, my life is so hard, people were mean to me, accompanied by the poor forlorn child help me look and that intense stare and asked me for hugs. I felt empathetic, sorry for her and got sucked in. Once we started dating, she became more 'normal', self-assured and confident. I thought she'd grown up and moved past that immature stage in which I had met her. Yet, in the end, when she left me for someone else, playing the victim to him in the same way (except in this scenario I was now the bad person she had to escape), she said she had "regressed". I could totally picture and imagine her acting EXACTLY the way she had with me, and it made me sick to my stomach to think about it. I hadn't seen that side of her in so long, I'd practically forgotten about it. I think that regression is when the mask slips. They go back to their old trick of the pity play, but it may only slip when they find another empathetic, vulnerable victim who likes them and seems easy to use. I think I read it somewhere that psychopaths periodically have the need to return to filth. When she finally told me, she said I would think she was "dirty". Months later she shed a tear in front of me and said she wasn't a good Catholic girl. Although some may disagree, I think psychopaths may not feel guilt, but can feel sorry for the repercussions their actions have on themselves, like losing friends or lovers. And yet, I think they can't control that urge to take advantage of a good predatory opportunity and have an incessant need to return to doing something dirty, wrong, clandestine, and reenact that victim dance. That, to me, is the letting the mask slip.