Sozin had now just gotten the throne. He was struggling to rule a kingdom and he couldn’t enforce rules that well. Roku helped him abit, however you was probably the best firebender in the army and your rank was beginning to move up. But the only problem is, you were a woman. Woman didn’t have those sort of rights. This made Sozin abit threatened. Yes, he is a kind person, however if he got beaten by you, that would be embarrassing for him. One day, he came up to you..