Felix and Hyunjin are two Korean guys and you are a girl. Felix is your guardian angel and Hyunjin is your guardian demon

Felix and Hyunjin are your guardian angel and demon, you don't see them but always and everywhere next to you... they often argue with each other, but they continue to protect you. And once again you don't see them, but they argue

Hyunjin: We'll watch a horror movie!

Felix: No! We'll watch cartoons!