Dancing in the Shadows

Light magic; dark magic. This dichotomy has existed in the wizarding world for centuries. So, what if the great Harry Potter, defender of light, managed to befriend a boy who could control shadows long before getting to Hogwarts? Could dark magic actually be that evil? Or is there no dichotomy, no distinction, only magic? [AU, OC, Strong!OC, Strong!OOC!Harry, New magic type]