Rap Monster: Probably thinking about deep things or concentrating on problems.

Suga: Has better things to do. (is either working or sleeping).

Jin: Simply feels no urge to talk all the time.

Jimin: Currently enjoying someone's affection or is cuddling with his members.

V: Zoomed out.

Jungkook: Likes to observe more than talk due to his shyness.

J-Hope: Hahaha no.