Jesus the Christ, pg. 8; “Thus it is shown that prior to the placing of man upon the earth, how long before we do not know, Christ and Satan, together with the hosts of the spirit-children of God, existed as intelligent individuals, possessing power and opportunity to choose the course they would pursue and the leaders whom they would follow and obey.” – Apostle James Talmage
Hebrews 1:5; “For unto which of the angels said he at any time, Thou art my Son, this day have I begotten thee? And again, I will be to him a Father, and he shall be to me a Son?”
So this apostle is telling us that Jesus chose the life he would live and Satan is his brother. Let it be understood this is a standard teaching in the Church.