Being a titanide and remaining always out of Olympic Pantheon, Hecate is referee to as a htonic deities, alongside with Hades and Persephone. In Greek mythology she was a goddess of darkness and witchcraft, had a power over ghosts, monsters, night visions.
Hecate as a grim deity firstly appeared in the Orphic religion in which she was called "that who rampages with souls of dead men". It doesn't look surprising that at the time of Ellinism she was getting more and more "dreadful" - at her presence nymphs hide in ravine. And right up to the Medieval times she became a full goddess of death, witches, necromancy, poisonous plants and so on.
In fact, Hecate is not dark, or black, or "brining the darkness" or she is not an embodiment of evil. Her duality, her ambivalent functions epithomyse a process of destruction for the sake of creation, the power of renewing through death.
Although she is also referred to a goddess of Darkness, Crathea (the name of Night Hecate), in the first place she symbolises a dark side of woman entity.
Of course Hecate is able to do evil, but this evil mostly for the sake of revenge. Due to her specific position as a titanid, she is not welcomed on the Olympus, but also she is not in war with it. Hecate accepts rejected, offended people, raped women, runaway slaves, revenges for their offences with terrible slow way. She can grow cruel plants whose juice, properly used, gives revelation, and in other doses can become fatal poison.
Thus, the dark side of the goddess, initialy planted in her with purpose to protect the weak, has been repeatedly distorted and demonised over time, depriving her dark side from fundamental sence - to provide the light with ability to spread.
