Hi Richard,
I'm not shy, socially, quite the opposite...but I am a caretaker so I didn't want to leave your thread unresponded to.

I do have a lot of empathy, used to be nearly a crippling amount.
So being an extrovert, and gregarious, doesn't necessarily mean less empathetic, imo.
I was thinking about how my heart always instantly melted when I met a man who was wounded. I have been involved with alcoholics, married someone partly paralysed with a broken back, a cancer survivor...
What is odd that all but one were also Ns. So I think the combo of N-plus-tragedy is the bouquet of red flags I know now I must refuse. (Not that I won't keep caring about people's suffering, but that I believe I must no longer sign up to dedicate my life to holding someone else up. I want reciprocal support, reciprocal caring, and reciprocal responsibility...)
Which all means I've sort of diverted your thread to a discussion about codependency, probably. Sorry. I'll yak about that elsewhere.
Shyness. Other words...intraversion? I guess shyness is intraversion + pain? Because just being a quiet type or mellow or contemplative sort doesn't have to make one uncomfortable or unhappy.
So I guess shyness might be intraversion plus fear? If the fear can be dealt with, a quiet person can be quite happy?
Hops