>>509928023God the Father created the demons and Satan. He can do whatever we want and it's not on us to judge what he does. Doing so is the ultimate vanity (that we can question God the Father).
See Isaiah 45:7 (God the Father does evil)
Job 1 and 2 (Satan obeying God the Father)
Romans 9:19-22
Pretty basic stuff if you aren't forced to believe something else by Men.