My cub

Remus Lupin, Sirius Black, Nymphadora Tonks and Bill Weasley returned with Harry and his friend to teach at Hogwarts. All of them drank an immortality potion to stay at their young ages. Harry at 19, and then the others all at their ages from when they ended the Battle of Hogwarts. Remus meets Emily and learns his Marauder friends have someone to protect.