I see you have a lot of questions.
I suggest you study the Bible.
And go to the FR Religion Forum and ask your questions of the Chirstians there.
God created everything.
Including angels.
Satan was created as an angel.
(therefore he can not be the brother of Jesus as claimed by the LDS church)
He fell from Grace and took one third of the angels with him.
They chose to folow him instead of God.
If God created Jesus and God created Satan, then they would be 'brothers'.