Spencer is a refreshing acquaintance due to the fact that he's similarly crazy smart and somewhat socially awkward as Brennan is. In many ways, he reminds Brennan of Dr. Sweets, their resident psychologist back home - quite young, brilliantly intelligent, but sadly misguided (in Bren's opinion) in his area of research. Only Spencer doesn't use air quotes and words like "awesome" like Sweets does - which is usually a plus as far as Brennan is concerned. Intelligence is soothing to Brennan, so she likes conversing with Spencer, even if I foresee some debate between them in the future about the scientific validity of what he does back home.