One Difference Is All It Takes - Rewrite

We've all heard the story of young Harry Potter, The Boy Who Lived. Many like myself grew up with Harry. But what would happen if there was a change? How much difference could one difference make? Join Harry and his twin sister Katrina as they change the wizarding world as we know it. Can The Twins Who Lived really change the world? Or will fate intervene? M for Future chapters!