How did I know I was in Harry Potter? Perhaps the supremely obvious clue of my name? Yeah, no. It was when Lily knocked over her glass of Tang, and with all the righteous might of nine year old about to lose her sugar intake, reversed it. Afterwords, she was positively beaming. As she looked at me expectantly, I patted her on the head. What? Don't judge me. [Severus Snape SI]