At the end of the final book, Harry Potter, the boy who lived, last hope for peace, the one chosen to kill the Dark Lord, bravely walks into the forest to meet Voldemort and imminent death. Instead of confronting Voldemort and his band of evil Death Eaters however, Harry is met by the ghost of his dead mother.
Lily informs Harry that Voldemort has never actually been in charge of the Death Eaters and that she has been pulling the strings all along. The Death Eaters are just following her orders to prevent "Chaos," in the world. You see, regardless of any proof Harry might have to the contrary, Magical people and non-magical people will never be able to get along. This means that allowing them both to live at the same time will always bring about death and destruction. It does not matter how many friends Harry has at his back, or how powerful the forces of good or evil are. The only way for him to (kind of) save the world is for him make one of three impossible choices. (Oh, and forget about the "Horcruxes," or magical objects that Harry was searching for in order to kill Voldemort, those were just a Red Herring).
Choice 1 - Harry must kill Voldemort. However, for some magical (and unexplained) reason this will blow up Hogwarts School and subsequently kill all Magical people, including Harry himself. On the positive side, it will ensure peace for all non-magical people for an unspecified length of time.
Choice 2 - Harry must cast a spell that will put him in direct control of Voldemort and his Death eaters, kind of like a puppet master. This will allow Harry to order the Death Eaters to kill themselves and ensure peace for the world. However, the chain reaction will blow up Hogwarts School, killing all of his friends and killing Harry in the Process. And no, Lily does not explain how Harry is going to control the Death Eaters after he himself is dead, he just can.
Choice 3 - - Harry must cast a spell that will kill himself and in the process cause his DNA to fly through the air and spread out across the entire planet. It will make every single living being both magical and non-magical at the same time. This will ensure peace and fluffy bunnies for everyone and their children. However, it will also destroy Hogwarts school and make flying on broomsticks impossible. Bummer.
After Harry makes one of these three choices, he dies in a blaze of glory, the much anticipated final battle with Voldemort is no longer necessary, the Death Eaters are no longer a threat, Hogwarts Blows up, and all Magical people are either dead or grounded because their broomsticks no longer fly. Ron and Hermione (who do not die) will suddenly be living in Cleveland (even though we left them at Hogwarts School a few moments ago). Ron and Hermione will embrace, stare out at the lovely Cleveland skyline and be joyful and relieved that they have survived this ordeal and get to enjoy their love for the rest of their lives.
Epilogue: A small child walks up to his grandfather in a Cleveland park and says, "Grandpa, is it true that people used to fly on broomsticks and cast magic spells?" Grandpa replies, "of course dear, and someday maybe you can too."