you were his cold and stoic beast servant so you were a female ajin (so an human with animal ears and a tail) pretending to be a boy ,beast servants could only be boys because they were stronger, to avenge your twin brother who got killed in his palace as his beast servant it was your duty to protect him with your life

he was very caring and kind ….

you were up early morning training as always when you heard him coming you turn your head to look at him