Raine is the professor at the school that Lloyd, Genis, and Colette attend. She is also Genis's older sister and could be described as the mother figure of the party. She is incredibly intelligent and mature. But when she is around ancient ruins, she goes into what is referred to as "Maniac Mode" and she becomes overwhelmed by all the potential knowledge that could be gained for such places.

Here is a reference scene. She is in Ruin Mode here but you can still get a feeling of who she is as a person from the scene.
https://www.youtube.com/watch?v=kcYdqHZCQIk