I'd say quiet

Talkative around people who get them....

Quiet in general but not quiet in specific.

I'd say that depends on the kind of intelligence. Like someone could be very aware of how useful having people like you is (hence talking and being friendly) and there are others I'm sure who would rather just keep to their own thoughts and keep out of inane conversation

I feel the fool in me is pointing towards the latter.

I presume you are doing fine, unlearn.