Fantasy Literature

The Sword of Gryffindor is a goblin-made sword that has a unique property: it only takes in substances that make it stronger. When Harry used it to destroy the Horcrux (the locket), the sword was imbued with basilisk venom, which made it capable of destroying Horcruxes. It doesn't rust or accumulate dirt. 'Fiend fire' is a dark magical fire, not related to the sword.

Dumbledore could speak Mermish, the native language of merpeople. This is mentioned in the series and is one of the reasons he could communicate with the Merpeople during the Second Task of the Triwizard Tournament. Gobbledygook is the goblin language, which Dumbledore may also know, but Mermish is specifically confirmed as one of his special abilities in the books.

When Harry encountered Bathilda Bagshot in Godric's Hollow, she was actually Nagini in disguise, and Harry heard her speaking Parseltongue. Mermish is the language of merpeople, Gobbledygook is the language of goblins, and Bulgarian is a regular human language.

Armando Dippet served as Headmaster of Hogwarts before Albus Dumbledore took the position. Grindelwald was a dark wizard and Dumbledore's former friend, Bathilda Bagshot was a historian and author of 'A History of Magic', and Professor Binns was the ghost who taught History of Magic.

Ronald Bilius Weasley is named after his uncle Bilius who supposedly died after seeing a Grim. Romulus is from Roman mythology (Remus's brother), Joseph is a common name, and Arcturus is from the Black family tree but not Ron's middle name.

The Sword of Gryffindor is a goblin-made sword that has the unique property of taking in only that which makes it stronger - it can absorb substances like basilisk venom to become more powerful without being destroyed. It was not made by elves, does not produce fiend fire, and being goblin-made, it actually resists dirt and rust.

Dumbledore could speak Mermish, the language of merpeople, which is a rare ability even among powerful wizards. While he could also speak Gobbledygook (goblin language) and many human languages, Mermish is specifically mentioned as one of his special linguistic talents in the series.

The Bubblehead Charm creates a large air bubble around the caster's head, allowing them to breathe underwater. Cedric Diggory used this charm for the Second Task of the Triwizard Tournament in Goblet of Fire. The Summoning Charm (Accio) was used by Harry for the First Task.

In Deathly Hallows, Ron Weasley uses Polyjuice Potion to transform into Reginald Cattermole, a Ministry of Magic employee, to infiltrate the Ministry and steal the locket Horcrux. This happens during the infiltration scene at the Ministry of Magic. Runcorn, Yaxley, and Dawlish were other Death Eaters or Ministry officials present.

Bathilda Bagshot was a famous magical historian and the author of 'A History of Magic', a standard Hogwarts textbook. She lived in Godric's Hollow and was an old family friend of the Potters and Dumbledores. She was not a Muggle, Daily Prophet reporter, or Dumbledore's enemy - in fact, she was murdered by Voldemort and used as a snake host.

Thestrals are winged horses that are visible only to those who have witnessed death. This is why Harry couldn't see them until after Cedric Diggory's death in Goblet of Fire. They pull the Hogwarts carriages. Being a wizard, Quidditch player, or specifically Harry Potter (before witnessing death) doesn't grant visibility.

Nymphadora Tonks is a Metamorphmagus, meaning she can change her appearance at will without potions. She frequently changes her hair color and style - often to bubblegum pink, which becomes her signature look. Metamorphmagi cannot change their Patronus at will (it changes with emotional state), don't change wands daily, and being a werewolf is her husband's condition, not hers.

During their Horcrux hunt in Deathly Hallows, Harry, Ron and Hermione listen to the Wizarding Radio (program 'Potterwatch') to stay informed about the outside world and the resistance movement. They cannot safely use owls (tracked), Patronuses (requires skill and may be tracked), or the Daily Prophet (under Death Eater control).

Harry discovers in Deathly Hallows that he is descended from the Peverell family through the Ignotus Peverell line. This makes him the true master of the Deathly Hallows, specifically the Invisibility Cloak which is a family heirloom. The Peverell brothers were the original owners of the Hallows according to The Tale of the Three Brothers.

Fleur Delacour marries Bill Weasley, the eldest Weasley brother, in Deathly Hallows. Bill was a curse-breaker for Gringotts Bank and was attacked by Fenrir Greyback during the Battle of the Astronomy Tower. Their wedding takes place at The Burrow and is interrupted by Death Eaters.