Merlin was the bastard son of Rowall Princess of Dyfed. His father was known as an angel who had visited her and left a child. Merlin’s enemies said his father was an incubus, an evil spirit that has relationships with women while they were asleep.
People suspected that the diabolical child, Merlin came to be a counterbalance to the good influence that Jesus had on Earth. Luckily he was baptized early in life, and this fact is known as the one which denied all the evil of his nature, but his powers still remained with him. He grew up being recognised for his powers and his possible destiny, for good or evil.
The story tell us that the roman withdrawal from England, was what made Vortigern run from Sachsen to Snowdonia, in Wales, in hopes of building a fortress. Unfortunately, the construction kept falling apart and the warlocks told him that the sacrifice of an orphan child would solve the problem. Merlin was known for not having a human father so they thought they could use him.
A few days before the sacrifice could happen, Merlin used his powers for the first time, he was able to see the future and saw a cave. In this cave there were two dragons, one white and the other was red. Which meant according to Merlin, that the red dragon represented the Bretons and the white one the Saxons.
Both had a fight and, at the beginning, the white one was winning, but after, the red dragon pushed him and ended up winning. The meaning was clear, it was a prophecy, that Vortigern would be killed and the throne would be taken by Ambrosius Aurelianus and after it, by his brother. That was one of the multiple times Merlin almost was killed.
The prophecy was right, Vortigern was killed and Ambrosius took the throne. After his death Ambrosius had as successor his brother, Uther.