Also, if Kami meant to kill you, she'd have had the portal lead to the lava. Even someone such as Appolyon would die in the depths of a volcano. Or have it lead to a room filled with nukes. By walking through that portal, you gave Kami the perfect chance to kill you, at the cost of only three minions. Had she not intended to use you, you would have been dead.
Furthermore, your symbiote protects you from her mind-rape.