Have you read The Necromancer?
Beware of the spoiler if not:
Mars gained the ability to control Josh when he Awakened him. Mars also gave Josh the knowledge of battle strategy.
Hekate, meanwhile, only Awakened Sophie's senases. Although I cannot be sure if Hekate would be able to control Sophie if she had not died, I think Hekate Awakened Sophie because she wants her to fight against the Dark Elders, and that she has no sinister intention at all; unlike Mars who was on the side of the Dark Elders back then. When Mars Awakened Josh, he asked Josh first if he's willing to pay a price.