The Second Side
The principle of the second side has been in existence even before the creation of man. This principle was introduced by God and influence by Him. No man actually wants his younger son to rule over his older son. This principle gives the younger power over the older. The fall of Lucifer brought this in.
Lucifer was a type of the son of God preferred above many Angels, he failed God, from there God had to introduce a second son who will bruise his head that will also have the same celestial body as Lucifer, to rule and take over the authority of the first son. Immediately this thought was conceived in the heart of God, it became established. I cannot tell if it stops after the resurrection of Jesus Christ. Jesus himself walked in this principle, Jesus is called the second Adam. The first Adam failed but the second Adam got the victory being obedient to God even to the death of the cross.