My Brother Is Really Not a Good Person

I have an older brother who is a leader of the sect, but he killed the father of the sect leader during his coming-of-age ceremony. Was it greed for power? Is it the desire for power? Or is it the bewitchment of a demon? For the first eighteen years, he was the beacon of my life. Eighteen years later, he is my revengeful enemy. Only by becoming stronger can we find the answer to the problem. My brother is really not a good person ?