My RB tabby Keke was notoriously shy, but occasionally she would fall in love with a total stranger (I had to pry her off the cable guy on one such occasion).

I once invited a law school class I was teaching (about a dozen students) to my apartment for the final class of the year. I expected Keke to spend the entire time under the bed. But no--not only did she come out to socialize, she made a beeline for the only person in the group who was allergic to cats.