Kasai
The girl's secret is that she's half human and half another type of alien. As a result of this, she has human abilities (telekinisis, in this case. Usually a low-level ability, but she has a LOT of power to amp it up. She's also stronger than normal for her size), and "dragon" abilities.
She can transform into a human-dragon hybrid, and into a full dragon form. Her power goes up with each stage of transformation. She doesn't tell ANYONE this, as she was made fun of and abused in different ways as a child because of this. Also, she has multiple personality disorder. The alternate personality is outspoken, has a temper, and protects Kasai. She can't transform into full dragon mode until she integrates her personalities, and to do that she has to make peace with her past.
Brown hair, green eyes.