What was Jesus' nature and role before becoming human?

The Lord Jesus' nature was Yahweh, in unity with the first and third Persons of the Triune Godhead. There was no role previous to incarnation because His role began when He became human. In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. - John 1:1-2 And the Word became flesh and dwelt among us, and we have seen his glory, glory as of the only Son from the Father, full of grace and truth. - John 1:14