The original leaders of the mission, Enki and Enlil, had lost much of their power early on, being the primary target of the plotting and scheming. Theirs was not a culture of violence and deceit, and so their leaders were not the ones who were best at these qualities.
Some of the junior crew members, however, who did not have the maturity and wisdom of their seniors, found that they were ambitious.
Among them, a young female started to obtain more and more influence, through manipulation, backstabbing, and an inborn cruelty towards others. Distrustful of stronger Anu but needing a male by her side, she roped in a low level technician. They were known by many names through the ages, but most famously as Ishtar (or Ashara) and Jahweh.