So the question that rumbles through some peoples heads are "Why are there Priests and Priestesses in a coven?" Well it's not just covens that have priests and priestesses. Churches also have them..
Priests and Priestesses, are like the parents of that particular coven. They guide the coven and keep order to it. Without a proper order established the coven would be in chaos a lot.
Some people think that a priest and priestess are rulers of that coven. Well in some ways yes, but some of the priests and priestesses do not acknowledge themselves as rulers. They acknowledge themselves as guides, parents..ect.
The same goes with churches, the priest and priestess or individual really don't call themselves the rulers of that church.
Some covens represent a god or goddess, so the ruler of that coven would be the god or goddess that the coven represents.