What is the overall storyline of jesus' existence according to john's gospel?

The gospel of John emphacizes the divinity of Jesus, the Verb that was in the beginning with God and became flesh, dweling among human race. Also the ministry of Jesus is explained, He came to his people and was rejected. The purpose of this gospel is that people believe that Jesus is the Christ, the Son of God. They that believe have eternal life and Salvation.

Explanation:  The Gospel of John is one of the four Gospels of the New Testament, the fourth in a row. While the first three Gospels together form a whole, the fourth Gospel of John is a whole unto itself. One of the verses that can be read in John's Gospel is the words of Christ himself who said that he, the Christ, is the way, the truth, and the life.  So it could be said that the overall story of Christ's coming and his mission is in fact the story of God's incarnation, when the Son of God himself came as a man and offered salvation to all who believe in him. This means that John's intention while writing the Gospels was to testify that Jesus Christ is indeed the Son of God in the flesh, for the Son (the Word) became flesh and settled and showed himself among his people, to offer them salvation.

the term used to describe a person that served a ruler or prince is courtier.