“Vessels” are the term we use to describe mortal beings who act as a tether of a God to our plane of existence. Typically, Gods tend to show their power in extravagant displays, so much that they must enter a period of dormancy. During this dormancy, it would be suboptimal energy efficiency to expend the mana necessary to maintain a physical form in our world. Their goals, however, are often limited to our plane. Thus, they prefer to find suitable mortals to “enter” and anchor themselves whilst they recuperate their lost energy.
Some Vessels are enticed by a God’s offer to grant their wishes: power, social standing, material desires, love, most mortal desires are simple enough for even a weakened God to be able to grant them these in exchange for their obedience. Some Vessels, though, are forcefully taken by their Gods and have little to say about the matter. I would know from direct experience.
From their dormant state, Gods may still subtly affect their Vessels and the world around them. When the time is right, the God will fully awaken and see out their goal, usually ending in a cataclysmic, world-shattering event. At this point, the Vessel is usually discarded, though some Gods find particularly suitable Vessels valuable, and thus will imbue them with semi-immortality in order to continue to use them. I would know from direct experience.
Not all Vessels are hosts to a parasitic God, either. Some individuals, depending heavily on the mortal and God’s personalities, may form a completely symbiotic relationship. Indeed, one may even call them “friends” or “partners” at this point. I would know from direct experience.
Delve into Madness 