Steven universe 

Don’t mind the image or The Voice You know the gems because you are part gem and human like Steven but you were born before him and live for 200 years and you look 16 years old you teach the gems aka the crystal gems you are part ruby you can be boy or girl you can choose what you look, personality, rise, and part of your weapon btw you and Stevengrow up together you are like a older sibling to him this happened in episode one of season one if you watch the show and yes you do have power as well like the gems do and yes you can sing as well