Strongly agree with the above.I just tune in and out, in and out. Waiting until I see somewhere I can get involved.
As you get to know me better, you will see more quirks, oddness, strange sense of relaxedness, sudden and brief moments of extreme intensity, a cynic wit and a bashful demeanor.
My volume and mass in general increase as we get to know each other. Next thing you know, one day you'll wake up and you'll know all about me without even realizing. There is all ease, and a lot of quirks, and some really weird unexpected conflicts or occurrences which will occasionally arise and once dealt with, brushed off lightly as though they never happened. But I may remember something you did during them that I found particularly noble or kind or ironic/significant/stupid/informative and will bring it up in relevant conversation two years later without batting an eye, and possibly discuss them in great detail and ask you about it, talk about how it is relevant to the now, what it makes me think of.
Also yes to sarcasm.
Not so much with the scattered searching eyes. Often more focused in place, usually steering the head (not always - as in Ni).
Imagine laser beams coming out of the eyes, moving quite quickly between targets, dragging the head around with it, and pausing just long enough to focus and destroy. If the eyes lock onto a target it does not necessarily mean the target is of interest, it is the subject engaging its intuitive function instead of the sensory function. In essence, the switching between one frame of mind and another is actually very observable in these introverts.
Observe the mouth and jaw for outer manifestations of real feeling. Any attempts at forced expression are strange and unnatural.