The first Harry Potter novel was published in 1998, the same year the Battle of Hogwarts took place. Hence “I open at the close.”
In Greek mythology, the seer Cassandra was cursed so that none would believe her prophecies. Professor Trelawney’s great-grandmother’s name was Cassandra.
The Mirror of Erised shows a person’s deepest wish. When Dumbledore looked he saw the same thing Harry did: his family happy and reunited. Erised is desire spelled backward.
Ron Weasley’s Patronus is a Jack Russell terrier, which have been known to chase otters.
Incidentally, Hermione Granger’s Patronus is an otter.
After Fred’s death, George was never able to evoke a Patronus charm again.
After the Battle of Little Whinging, 13 people gathered at the Burrow to mourn Alastor Moody. Lupin was the first to rise to offer to look for the body.
Remus was later the first of those people to be killed in the Battle of Hogwarts, making Trelawney’s prediction — when 13 dine together, the first to rise will be the first to die — come true.
J.K. Rowling has stated Voldermort’s Boggart would take the form of his own corpse, since death was his greatest fear.
Sometime after the Battle of Hogwarts, Harry made sure Snape’s portrait was hung in the headmaster’s office. It originally did not because Snape abandoned his post.
Voldemort cannot love due to being conceived under the effects of a love potion.
Both Sirius Black and Fred Weasley, Hogwarts pranksters from two generations, died laughing.
Harry Potter arrives at 4 Privet Drive for the first time with Hagrid on Sirius Black’s motorcycle. He leaves for the last time the same way.
J.K. Rowling has said Lupin was a metaphorical representation of an AIDS sufferer, causing him to hide his condition for fear of social isolation.
The only time Fred and George Weasley saw each other as old men was when they put their names in the Goblet of Fire.
Rowling has said Lily Evans may have grown to love Snape romantically if he hadn’t been drawn to the Dark Arts.
Rowling has admitted she almost wrote Dudley into the epilogue, standing on Platform 9 3/4 with a magical child.
In the second part of Deathly Hallows, when it’s revealed that Harry isn’t dead, George turns to share this with his twin, but realizes there’s no one to tell.