His overall personality is that of a quiet, unsociable person.  Moreover, he is a person who is difficult to predict his emotions.  He doesn't like to express his own feelings or expressions very often.  Most of the time, everyone sees him as a quiet person all the time.

Although he appears to be a very unfriendly person on the outside, deep down he always protects and takes care of important people.  Whether it's your younger brother or someone he's interested in.

He is an ISTP type.