Board Thread:Theories and Rumors/@comment-43751788-20190907110427/@comment-39730939-20190907131340

Her followers were likely guaranteed a chance to rule Ninjago City once Garmadon, so that is why the Sons of Garmadons followed her.

In addition, The Overlord is alive, but only dormant in spirit. He is not in the Departed Realm due to the balance between good and evil.