A witch never starts out able to wield Dark Magic. Dark Magic was witchmade, not natural in any way. It messes with the makeup of human nature - life in all things. Dark witches and warlocks practice breaking the bonds of life within every living thing, throwing the system into distress. The magic involves bending laws of the coven that protect the sacredness of life - manipulating the innerworkings of the body, the level of life left in someone, sucking life for themselves out of the earth. They mix potions to create witchmade creatures, bending to their will. They are wicked, they are seething, they are waiting for their moment of up rise to come. They practice in secret, with past prejudices in the coven against these witches and warlocks, many keep their preference hidden until it shows on its own - a mark on the back of their neck that takes years to form, tireless practice to perfect, an immense amount of energy to gain.