Flower: the Rather Reluctant Fifth Marauder

Serena Wendal never wanted to be a marauder. In fact, she never wanted to meet the marauders in the first place. But when you're extremely shy and afraid someone will find out your (admittedly pretty lame) secret at any moment, the universe doesn't really care what you think. Yes, it's an OC story, but give it a chance? Main focus not romance, but story and friendship.