Ain't as cute as you think

My heart is pitch black, yet I'm talking to my best friend in class as if I'm innocent. I have done so many things, dirtier than the other. So tell me Thai, my closest friend, where do I belong to? Have you never asked yourself why I'm so skinny? Why I dye my hair? Why I have only my stepmother, who disappeared? Why I'm always so tiered in school? Why I'm sometimes gone for a few weeks? Why I seem so weak yet win in a fist fight against an obviously stronger man? Tell me, why are still with me?