Love and Hatred are the 2 most powerful emotions. Fear is an important one, but not the most powerful. Fear just stops someone from doing something. On the other hand, love and hatred can drive someone into doing anything.
In order to love, you push yourself to the limit. You can just do about anything for your lover/love. Like in those romance novels, sometimes the characters can commit murder just to "steal" someone back to him/her.
Hatred is exactly the same as love, just in the opposite direction. Hatred is the negative emotion (and love is the positive one) that can drives people into doing anything. In order to rid/satisfy your hatred, you have to destroy the thing you hate, or at least turn the table around to that it's in your favor instead of the other way around. Other more specific emotions come from hatred, like for example, hunger for power. Hunger for power comes out of the hatred of society, or the hatred to be under control/manipulated. Only if you have power, you won't be in control or manipulated by someone else, and in return you'll be the one to manipulate others (which stimulates the hatred in someone else and thus the evil cycle begins)