Cassie is a main character and POV character in the Natural Series. She's empathetic and rather lets things get to her as she is quite a compassionate person. She's a natural profiler, meaning she can pick on the personality of other people based on a few bits of bodylanguage and their actions, after that being able to determine their way of thinking and piecing togheter their nature. Overall she appears to be a caring person and wants to do the right thing in situations that are dire and even those that will make people happy. Her talent for profiling lands her a spot in the elite FBI program for teens with impressive crime-solving abilities, which gets her into some harrowing situations.
Dean is a part of the Naturals Program that Cassie is also in. He's a profiler and Cassie's boyfriend. His dad, Daniel Redding, was an infamous murder, which had a major inpact in his life and the lives of his friends that were also the only ones he considered to be his family. He has a kind soul but his backround made him to emotionally shut down when it came to letting people in his life and some part of him is also scared that he'll become like his father and hurt everyone around him.
Lia, the human lie dector or the natural liar is intelligent and sharp with her words, she's not very open about her past and her true emotions are always masked with thick layers of deception. She's always changing her clothes and taking on diffrent personalities depending on her mood that day. Many might find her mean and heartless at times but behind all her walls she cares about her friends more than she will ever let out.
Sloane is very quirky, but also sweet and caring. She is always analysing people and situations, most times without even meaning to. She loves to unexpectedly say some random facts that are on her mind at the most unfit times. She takes comfort in numbers and facts since nothing in her past was stable, but numbers were precise, analyzing every little possibility in all situations encountered. She's not the best at meeting people or making friends so she tresures her few friends that are also her family.
Michael locks away his feelings behind a tight mask and rarely shows his true emotions, much like Lia which resulted in their comlicated history later on. He was an emotion reader, he could take one look at a face and know exactly what that person is feeling, he could read the most difficult people and often especially the ones who would give anything to keep them away and hidden from everybody. When he's upset he always tries to brush it off with humor and attempts to not show vulnerability. He also has a tendecy to throw himself into the path of danger fot stupid reasons.