Dr. Katherine Gilchrist is a coworker of Monica's at the museum, where she is a textile expert. Introverted and a bit spooky looking, it was difficult for Monica to draw her out of her shell, but the effort was appreciated.
Her pre-existing hobbies are mostly solitary ones. She has a pet betta fish Oscar, and some unsuccessful plants. She collects spiders. She's also a nudist, although only in the privacy of her apartment - Minneapolis is a location which demands plenty of clothing for the outdoors.
Over time she's gotten to meet quite a few people and enjoys social activities...at least in theory.
The story arc "Katherine Gilchrist and the Lost Dolls of the Anasazi" took up much of 2013 and went into more depth on Katherine's background and history (start reading here). There is much more to her than meets the eye - or, should we say, eyes. The storyline arc was "adapted" into a written novel format by Joseph Houk, available at Google Drive. (A non-eBook format version is available here.)