Twins, Meredith and Lexie Grey, 16. Complete opposites. Meredith: senior, smart, quiet, black sheep of family, secretly athletic, bookworm, few to no friends, skipped a grade, spends free time in the library, introvert, shy, responsible, Lexie: junior, average intelligence, loud, fits in everywhere, queen bee, captain of the cheer squad, dates the jock, Mark Sloan, spends free time at the mall with her girlfriends, extrovert, not quite as responsible.