At 105-years-old Harry Potter is still called the Boy-Who-Lived. His great-granddaughter seems to this funny and compares him to a fictional character who also remains a boy forever. Harry muses about this character and their differences and similarities.
Post DH. Albus writes a letter home to his parents after the nerve wracking first day at Hogwarts. He tells his parents about the sorting, the castle, the common rooms-did you know there is a Giant Squid in the Black Lake? - old friends, and new.