One of the most underrated interpersonal skills is empathy. Being able to truly put yourself in the shoes of another and not only see their perspective, but feel their perspective is true power.
Understanding how someone views a situation, what they care about, and what their motivations are gives you complete power and control. Often, the true motivations of an individual are veiled, both to outsiders and to the person themselves.
As humans, we not only want others to believe we have pure motives and intentions, but we also want to believe that we ourselves have pure motives and intentions. This involves deception at the deepest level; the deception of ourselves.
Get to the heart of one's deepest, true motivations and you can work with them, help them, and yes, manipulate them.