When we talk about "moodiness" I assume we mean a withdrawal of happiness and being upbeat..into a place where saddness is.Then a person may be in need to be alone and the very effort of being in company is difficult.I accept that in a person
But surely all variations of feelings are but moods.Like the sun changes the earth as it moves across the sky.
Like Anno a child who shows no emotion is a difficult being to help.Light and shade add interest.
Mountain ash