With a teen, I would imagine it would be much like an adult. It would likely revolve more around academic performance, interactions at school, and family life. A 13 year old may not be able to comprehend everything as well as an adult so it would be important to find a therapist that he/she could relate to, i.e. someone that has experience with teens.
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Igor: "Abby something"
Dr. F: "Abby who?"
Igor: "Abby...normal"