User blog comment:B214/Question and Answers/@comment-187.133.44.229-20130812062539/@comment-1359322-20130812063155

Angels can also fall if they have evil thoughts. Like the Top Level Angels that fell for joining Khaos Brigade. The main reason to falling is if they divert from the teachings of the God from the Bible. But since he's dead and Michael took over, it wasn't strict as it was before.