After the end of the Wizarding War Kingsley got a letter written by Dumbledore before his untimely death which divulged some never before seen secrets and a wish of him that he wanted Harry to be the Defence against dark the arts teacher. But Harry decided to become an auror and repudiated the post of defence against dark arts teacher. Also he decided that he would never go back to Hogwarts, the place where he spent six years of his life. But in the end he did return and unbolted another "riddle".