If you are talking about the Dead Three, then this is also a story about mortals achieving godhood. And it is not the source of everything that happens later on. For example, Irenicus has lost his elven spirit (or whatever it was they have), because he tried to usurp the power of the tree of life. Failing on that, he tries to get divinity again by stealing the divine soul of a Bhaalspawn first.
The initiative starts with mortals. Bhaal was mortal too, before he became a god. This is how the story starts: the Dead Three make a pact: they will become gods or die trying.
