Living as an immortal and the great ruler of the night has its perks. People don't dare go against you because they know the consequences. Also, with everyone scared of you, it gives you more time alone. Nobody to worry about, waking up each morning to the sound of silence that is very comforting and relaxing.
Going to hunt for food when you want, with no need to cross paths unnecessarily with silly humans or even have a conversation with them unless they're food. He didn't feel pain, joy, or fleeting emotions, which can be a hassle. These were the perks Kael had enjoyed until now. He never complained; in fact, it was the best thing about being a vampire king. He was one happy soul, what people saw as loneliness and twisted, he saw as freedom.