I think PA like to punish those they are close to and emotionally dependent on. In fact I think it is one reason why they often leave us, often, because they are terrified of abandonment, and so they run first.
So they screw our birthdays upnfor example. Part of them hates themself for it, but the other part of them is quite deliberate about it. I think one problem with PA is that their "adaptive" child part of their personality is out of control, and actually dominates both the free child and what should be the dominant adult voice. The adult and free child are a bit frightened of this out of control character and spend a lot of time pretending it doesn't exist, and never address it. It really is a manipulative and covert part of their personality which they are pains to deny to themselves and others, rather than addressing it. Many PA behaviours stems from this - the blame, spite and manipulation, in a person who has many many good qualities which get quite over-ridden.