In Heat Wave, she is described as being from the projects in St. Louis and having an almost photographic memory for all the autopsies she has performed. She also teaches occasionally at Columbia University and has a dachshund named Lola. Like Heat and Lanie she is single, though in Castle's second Nikki Heat book, Naked Heat, Nikki spots her and a newly-single Detective Ochoa going out for breakfast.
In Heat Wave, Castle describes the two women's relationship thus:
"Despite cultural differences...they connected on another level, as professional women navigating traditional male fields...[Nikki] and Lauren clung to their camaradarie and the sense of safety they had crafted for each other, to have a time and a place to share problems at work, largely political, and, yes, to decompress and let their hair down..." 
- Heat Wave, page 112
- Heat Wave, page 63