She's like a tornado, or perhaps a hurricane, consuming everything in her path and tossing it back out again, damaged and mangled. She's wild and dangerous; she's the only Slytherin in the family, and considering how many people are in said family, that's saying something. She's beautiful and risky and forbidden, and perhaps that's why you are so attracted to her.
You've always liked the idea of being bad, but you never had the guts to do it. Perhaps being with Lily is where you can start, because she's the epitome of a bad girl, and you like it just a little too much.