Professor Dumbledore?

As Albus stared at the eyes of a little boy, he made a decision. To hell with the Greater Good, to hell with Tom Riddle, and to hell with prophecies. They can all kiss his ass for all he cared. Or in which Albus Percival Wulfric Brian Dumbledore decided that he was too old to give a damn anymore, and gave the Headmaster position to his 18 year old son.