NO, they (Jesus and Satan) are not brothers in any way shape or form.
There are many references to the eternal deity of Jesus Christ, eternal with the Father from all eternity to all eternity. The focus of all scripture is on the person - and work - of Jesus Christ - which is why this question is KEY to everything about Mormonism contrasted with the true truth of God's Word and reality.
Colossians 1:9-18:
9 For this reason we also, since the day we heard it, do not cease to pray for you, and to ask that you may be filled with the knowledge of His will in all wisdom and spiritual understanding; 10 that you may walk worthy of the Lord, fully pleasing Him, being fruitful in every good work and increasing in the knowledge of God; 11 strengthened with all might, according to His glorious power, for all patience and longsuffering with joy; 12 giving thanks to the Father who has qualified us to be partakers of the inheritance of the saints in the light. 13 He has delivered us from the power of darkness and conveyed us into the kingdom of the Son of His love, 14 in whom we have redemption through His blood,[c] the forgiveness of sins.
15 He is the image of the invisible God, the firstborn over all creation.
16 For by Him all things were created that are in heaven and that are on earth, visible and invisible, whether thrones or dominions or principalities or powers. All things were created through Him and for Him.
17 And He is before all things, and in Him all things consist.
18 And He is the head of the body, the church, who is the beginning, the firstborn from the dead, that in all things He may have the preeminence."
Of course I do my own studying. I too was searching for the TRUTH about life, about God, about the Bible, about Jesus Christ. So I searched the Holy scriptures, I searched the "alternative scriptures" also, such as the book of Mormon and other "religious" texts including the Koran. And I am not afraid to talk with anyone about the true truth about God, about Jesus Christ, about the Bible, and about the "alternative" scriptures / "faiths" / in the world.
My hope and prayer would be that every individual who craves to know the TRUTH will do such a search.
Back to that later maybe....
What I show you was from the Bible!
Jesus is the only begotten in the flesh Son of God!
But we are all sister and brother in the spirit, before we arrive here!