Thirteen years after the war.
Harry saw the head of the Malfoy family again at Platform Nine and Three-Quarters. He was no longer the boy who had just stepped into the world of magic.
Malfoy, meanwhile, was now a middle-aged man facing a receding hairline.
It had to be said that the once-arrogant Slytherin prince looked far more weathered than his father, Old Malfoy, had at the same age. He was with his wife and son, and the child looked so much like Draco as a boy it was uncanny.
For a moment, Harry was dazed. He remembered that day, and the hand he had pushed away.
And then, a lifetime passed.
“Dad!” Harry was pulled back to himself by his son Severus calling out to him. His wife, Ginny, looked at him with concern, just as she had the first time he met her. There was nothing more to it, he knew. What Ginny felt for him wasn’t love. It was affection and admiration, not love.
They were no longer young.
And he had lost the one he loved forever.
Thirty years after the war. Harry Potter, the great Chosen One, the youngest headmaster Hogwarts had ever had, and a master alchemist, remained at Hogwarts School of Witchcraft and Wizardry forever.
His portrait hung in the Headmaster's Office, the only portrait of a Muggle.
There are quite a few changes to canon, but I’ll try to keep everyone in character.
One more thing, a heads-up: Harry here is a middle-aged wizard who has served as an Auror captain, Minister for Magic, and headmaster of Hogwarts, and is the father of three children. He’s got a tough, outwardly mild but secretly ruthless personality. Draco, on the other hand, is an actual child. So in the early chapters, think of it as Harry’s dad giving little Draco a lesson.
There are children, but no mpreg. They’re the product of alchemical science.
Premise: Get it right the second time around, and take control of the whole situation.