How about this:

Power is the ability to control. Control follows responsibility. You have exclusive responsibility for yourself and over your choices because no one else can possibly have control over that, unless you acquiesce and give it to them first. Likewise, you have no control over the choices of others and therefore no real power over them. Whenever we try to control things over which we don't actually have any control, especially when using underhanded emotional tactics, we become powerless because our efforts are doomed to failure. We give our power away whenever we allow others to succeed at illegitimate power grabs from us. And finally, we become powerless whenever we abdicate our responsibilities.

When you say alliances, I suppose you mean in the sense that a company is a complex alliance. As an employee, I agree to give a certain amount of control over my resources in exchange for a paycheck. This would be an example of a legitimate extention of power by one person over another because it represents an exchange in which both parties are better off.