A forensic female investigator with sexual appitites for any thing new and dangerous. She has seen it all and had tried it all. Her only motivation is to make all guilty perps face the music.
Every man has the fantasy of being a doctor and getting to examine a young woman. To have her think of him as an authority figure, someone whose orders are to be obeyed. Harvey harbors just such a fantasy. This is the second such episode, after Annie has started college, her friends have scattered across the country, and his built-in linkage to young woman in the community has fizzled. In other words, it's time for circumstances to work in Harvey's favor, and fulfill this latent fantasy.
Betty is a 60 something gal who loves sex and especially likes to entertain herself with young men, two at a time, while riding a cross-country train. Climb aboard because Betty likes to kiss and tell.