LightBearer,
Jesus and Lucifer are not and never were brothers. Please continue reading and I'll prove it.
Jesus and the Father (Jehovah) are One. They are not just One in power, but One in essence... Yet they are distinct in person, in function, in "ministry". When people said that Jesus was the chief agent in creation, they weren't referring to Him as God's hired help. The truth is that Jesus WAS the chief empower (if you will) in creation because St. John 1:3 clearly states that "all things were made by Him." But, we know that God the Father had a role in creation... for He SAID, and then He SAW. But, understanding their triune nature, you can understand that the two are ONE and so Jesus is Jehovah.
The distinction comes in when you refer to the ministry of the Father, the Son, and the Holy Spirit. Remember that Isaiah 9:6 says: "For unto us a child is born, unto us a son is given..." The child (the human baby, the man-nature of the Christ) was born, but the Son ALWAYS existed, hence He was given.
Now, you claimed earlier that He was the first thing created. But, John 1:3 is CLEAR to state the ALL things were made by Him, Jesus. ALL means all. Since we know that He can't make Himself, then He must not be a "made" thing. He has always existed because He is God.
Now, as it relates to Lucifer, the sonship of the angels is totally different than the sonship of the Son, Jesus. I've already showed that Jesus IS Jehovah. So, that proves that in His divinity, Jesus is NOT Lucifer's brother, but His God and Creator. But, let's examine Jesus in His humanity.
Question: are humans and angels brothers? NO. The angels are not referred to as sons of God meaning that they are begotten of Him... but that they are subservient to Him. So, in the idea that we all SERVE the Lord, there is a "brotherhood" because of the commonality... But, we are not brothers by nature. And so Jesus, in His humanity, is not a brother to Lucifer either. Scripture refers to sons of God because they are servants of God, not just because they were created by God. If that were the case, sinners would be considered sons of God, but they aren't. So, again that shows that the sonship comes from service, which fosters a brotherhood, but doesn't make us BROTHERS.