His best friend was his subject, but he was more loyal to the blood moon race than he was to him.
His best friend was faithful enough to give his all, including his authority, power, and life, to eradicate his king's newborn son.
Actually, at that time, the people didn't consider Vincent as the crown Prince or the king's only son. Instead, they labeled him with the title of the harbinger of destruction, a menace that someone had to purge before it dooms them.
Aaron knew that, so he had no choice but to make his move. Rather than waiting for his best friend to come and kill his child, he went out to stop him instead.
By the time he reached there, his best friends had already grouped up with many who were against him and in collaboration with him to take him down and then kill his child.
In a sense, they have started a rebellion and wanted to strip him of his right as the ninth king.
