After Planet Caelmir awoke several billion years ago, Magnus left and never returned. He lost everybody who believed in him, so he had no reason to stay there anymore.
Of course, after the planet's awakening, all who despised him gained a reality check and tried to make it up to him. However, they were too late.
One of those people was his father, who was the king at the time.
Before the awakening, he treated him like shit. He hated him simply because he awakened as a Vampire, the only vampire the world had ever seen.
However, after the awakening, or maybe during the awakening, when the danger level reached a certain stage where even he was struggling to keep his life safe, he finally saw that the vampire he hated was the only one standing tall, defending the planet from the heavens.
He hated himself for that, so after the awakening, he stepped down as king and exiled himself, spending the next billions of years reflecting on his life and finding a purpose.
