Happy little accidents

Since the day the two young boys met they hated each other. To Draco Harry was a good for nothing know it all, and to Harry draco was just a spoiled brat. Draco decided he would trick Harry into becoming friends in order to betray him for his father but what will the two boys do when an accident in potions leads to Harry becoming a four year old boy, and Draco slowly unravels the truth of the boy that lived through hell?