The young man was not a servant of god, nor was he a creation of god, though a free thing that came close to his equal if not his friend.
The angles noticed that Lucifer and God spent a lot of time together, and something from days on end the castle's doors where unopened. which was unusual as God kept them open always.
Michael did not like it. He did not like it at all.
One day, as he flew across the void, a feeling came to him. One that he could not comprehend. One that ate at him. That turned his insides to goo, whenever Lucifer's name was mentioned. He wanted, he later on noted, to either be him, or get him gone at the very least. He was sure he hated him. yes that was the word, he absolutely hated him. He hated his yellow hair, his bright, lovely eyes and that stupid zeal to his voice whenever he talked about souls, and hearts and benevolence.
'This has gone too far.' he told a group of angles that met secretly under the stone dome on that very evening.. 'We must get rid of him.'