I will keep this sweet and simple cause I know you're all too autistic to think past psychiatric / npc terms.
So focus.
DPD's survive by adopting the most fitting personality to adapt to their host, like parasites.
They're usually devoid of ego, pride, strong opinions, and they got no competence or any form of independence due to how is part of their disorder.
That type of personality is exactly what someone who wants to feel dominant and in control seeks out.
Now before you go "not all people are like that, that's only npd's/aspd's or machiavellians" blah blah.
You're wrong.
Machiavellianism in fact its self, is highly depended on filtering your words and actions to not - provoke the ego or anger of others.
That's exactly what DPD's do as well, but unlike machiavellians they do it cause they want to survive/ not accomplish anything.
I met many DPD's in internet and in real life, they had the highest and most flexible social engineering personalities. They were anti-competitive and never caushed any trouble, they also constantly attempted to be either neutral or likable, or something in between.
I also knew a girl irl who was similar to that, I would try everything to make her sperg and nothing would work cause there was nothing she couldn't tolerate, she ended up begging me 2 AM outside my house and ringing my bell. Literally no shame at all.
And the worst part is, machiavellians have some sense of pride/dignity they cherish and keep hidden, they don't let it affect their functionality sure but. It's still there.
DPD's don't care, just allow them to latch on you.
For these reasons DPD's are far more difficult to deal with than npd's/aspd's/machiavellians, their lack of hostile intent makes them wayyyyyy too adaptable to practically everyone.