I did the tests on http://www.9types.com, and it seems that I'm a 4 as well, for the most part. I can identify with getting progressively moodier/crankier with age. Why did I do that?
(How old is your W? I'm in my early 30's, and already ran into trouble with moodiness and crankiness.)
Fear of being defective -> indulge in fantasy -> understand themselves -> Fear of being defective In the unhealthy state, the basic fear of being defective can cause Type Fours to ignore their true selves, allow their emotions to overwhelm them, and indulge in wild fantasy about themselves. This means they will understand themselves even less, and further increases Fours' basic fear. The cycle continues to build up
Of course anyone who "allows their emotions to overwhelm them" will tend to be moody and sometimes cranky. Also, anyone who believes that they are defective will resent anyone else presenting evidence of their defectiveness or looking for anything that might furnish evidence of their defectiveness, since they're trying to push their defectiveness out of their minds and keep your attention away from such defectiveness. Any attempt to know them closely can feel to them like gathering evidence with the purpose and effect of convicting them of their defectiveness.
a fine and enviable madness, this delusion that all questions have answers, and nothing is beyond the reach of a strong left arm.