Dr Robert doesn't answer questions here generally, so you should email him instead. I will however answer your question. It's a subconscious thing. Some people just scream "abuse me". There are no definitive traits because everyone tries to be something they are not. So from a "predators" point of view, you just know.
Cool thanks for your honest response. So basically I think the answer is you become a victim if you let someone do it. I personally think if you are a bit inclined to look weak in some way or act unconfident or depressed it invites it too. There are lots of behaviours you can learn to ward this stuff off. The other side to it is the "predator" can become honest to themselves about liking many people and just declare themselves as polyamorous. Anyway thanks for your reply and I'll direct the discussion toward Dr.Robert in an email.
You asked about this: "partners/followers of manipulative people are often very compassionate and nurturing people, who are often quite the opposite of the person they love."
This is frequently the case regarding "nurturers." I believe it may be because a confirmed nurturer--particularly one who prides herself/himself on being a nurturer, or "compassionate"--often will continue to put up with constant manipulation, whereas a less "nurturing" person would simply walk.
Actually, true compassion is not at all sentimental--in fact is the very opposite of sentimentality--and does not lead to being victimized.
Thanks for that, Dr.Robert. These are wise words indeed. I will pass this on to my friends who may feel they are being used or led astray. I think you've just answered my question of why it is unethical for a friend or a lover to become the counselor of that friend too, I think its for that exact same reason (and that they aren't trained in the area so may offer the wrong advice.) Cheers :-) P.