Warning! SPOILERS for Return to Hogwarts.

Harry Potter 20th Anniversary: Return to Hogwarts came out New Year's Day 2022 and here are all its grand reveals. The movie opening saw the main cast receive Hogwarts invitation letters for an event marking two decades from the first movie, Harry Potter and the Sorcerer's Stone, in 2001. The emotional reunion brings cast together - some of which haven't seen each other in years - and opens up discussions about the making of the eight movies throughout 10 years. Some of the topics explored by the cast and crew in Return to Hogwarts are brand new to the viewers.

Throughout the duration of the original Harry Potter franchise, the movies became loaded with prominent actors (that, as it turns out, strongly impressed and intimidated the young cast). Although there are quite a few Return to Hogwarts sees several main actors on screen: Daniel Radcliffe (Harry), Emma Watson (Hermione), Rupert Grint (Ron), Jason Isaacs (Lucius Malfoy), Tom Felton (Draco Malfoy), Ralph Fiennes (Voldemort), Gary Oldman (Sirius Black), Helena Bonham Carter (Bellatrix Lestrange), Matthew Lewis (Neville), Robbie Coltrane (Hagrid), Bonnie Wright (Ginny Weasley), and James and Oliver Phelps (Fred and George Weasley) included.

Related: How To Watch Harry Potter's Return To Hogwarts Reunion Online

HBO Max was able to gather a huge number of people for Return to Hogwarts, and this goes to show just how beloved this series remains to so many people. As the stars gather on the original Harry Potter sets to look back at the franchise's legacy and the making of the films, they sometimes surprise each other with personal memories from the 2001-2011 decade. Here are all the big reveals and secrets from the Harry Potter era.

1. Chris Columbus Became The Harry Potter Director After His Daughter Made Him Read The Books

Director Chris Columbus in an interview

For the first time in 20 years, Daniel Radcliffe asks Columbus how he got to be the director of the first two Harry Potter movies. Columbus shares that it was his daughter Eleanor who made him read the Harry Potter books after he refused three times. When Harry Potter and the Prisoner of Azkaban came out, Columbus read the three books and immediately envisioned the movies, which, according to him, had never happened to him before. He then flew to Edinburgh to meet J.K. Rowling and discuss his vision for the first film, to which Rowling said, "That's exactly the way I see the movie."

2. Daniel Radcliffe’s Parents Didn’t Want Him To Take The Role

Daniel Radcliffe in Harry Potter Reunion Return to Hogwarts

While Harry Potter producer David Heyman had the inspiration to find Dan's parents at a theater in London and convince them to send Dan to one audition. The rest is history.

3. J.K. Rowling Created A Quidditch Rule Book For The Movies

Draco pursues Harry in a Quidditch match in Harry Potter and the Chamber of Secrets

As the audience had to understand the game rules immediately in order to follow the very dynamic scenes, J.K. Rowling wrote a special book "explaining every detail of the game" for Chris Columbus and Stuart Craig, the production designer who ended up creating an authentic and impressive pitch that's ed by millions to this day. Rowling and Craig worked together to help viewers visualize the exciting, but dangerous Wizarding World game.

Related: The Biggest Questions The Harry Potter Reunion Won’t Answer

4. Jason Isaacs Initially Auditioned For Lockhart

Lucius Malfoy looking sinister in Harry Potter

Perhaps surprisingly, Jason Isaacs wanted Gilderoy Lockhart's part, which eventually went to Kenneth Branagh. Columbus then told Jason, "That was great. Would you mind reading a different part?" Jason was initially annoyed at not getting Lockhart's part, and because he was about to play Captain Hook in Peter Pan (another villain), he turned down the offer to play what has now become one of the greatest (and most skillfully portrayed) villains in Harry Potter. Jason is convinced he got the part because, ironically, he didn't want it. He read the audition "through gritted teeth, deeply bitter" and, of course, that helped him get the role of Lucius Malfoy.

Both Jason Isaacs and Tom Felton (Draco Malfoy in Harry Potter) explain that Lucius was an excellent means to explain how Draco is a product of his parents: a sadistic bully that would end up forced into becoming a Death Eater. Tom also confesses he was impressed at how Jason would immediately transform into "the most unfriendly, horrible person" as soon as he heard the cue. However, he would become cuddly and protective of young Tom, as soon as he finished his lines.

5. Daniel Radcliffe And Gary Oldman Were As Close As Harry And Sirius

Sirius hugging Harry

When Dan first got news of Gary Oldman ing Harry Potter, he told Emma to "be cool because Gary Oldman is a big deal," projecting his own enthusiasm about it. Gary says that he had a "natural sort of paternal thing" towards Dan, who was 14 at the time of Harry Potter and the Prisoner of Azkaban when Sirius Black first appears. Moreover, Harry Potter director Alfonso Cuarón re how Gary included Dan in the acting process, immediately forming a bond with him. As the third Harry Potter movie is essentially a coming-of-age film that sees Harry, Ron, and Hermione slowly become adults and embrace the dangerous life ahead of them, Sirius is a key paternal figure to Harry, and so was Gary to Dan in many ways.

6. Alan Rickman Requested Snape’s Backstory From J.K. Rowling

Snape holding Lily's body while Harry cries in the background in Harry Potter

Alan Rickman knew Snape's whole backstory: his apparently shifting loyalties, his ultimate loyalty to Dumbledore, and his undying love for Lily Potter, which motivates him to help and protect Harry in his quest against Voldemort. He knew of Harry Potter's future timeline before anyone else, including the directors, and that is because he went to J.K. Rowling and requested Snape's history, as he figured out Snape was too complex a character to play him without knowing all the layers. Dan tells Gary about it: "And he never told Chris [Columbus], he never told anyone. Chris would literally say to him, why are you doing that like that? He was like, I’ll tell you later."

Related: Harry Potter: The Dursley's Xmas Gifts Set Up The Hallows - Theory Explained

7. Emma Watson Had A Crush On Tom Felton From The First Film

Hermione pointing her wand at Malfoy in Harry Potter and the Prisoner of Azkaban

During tutoring on the set of the first Harry Potter, the actors were given the task of drawing what they thought "God looked like." Tom drew a "girl with a backward cap on a skateboard" and that made Emma fall in love with Tom. She would then get very excited if she would see his number on the call sheet, and look forward to every moment spent with him on set. Emma was 10 at the time, and Tom was three years older, so he always regarded her as a younger sister. Tom says he became "very protective of her," and in Return to Hogwarts, both Emma and Tom profess their unromantic love for each other, a love that carries on to this day.

8. Ralph Fiennes’ Nephews Made Him Take Voldemort's Role

Voldemort playing with the Elder Wand in Harry Potter and the Deathly Hallows Part 2

Ralph Fiennes confesses it was his sister Martha's children (who were around 10-12 at the time) who overheard him telling Martha he wasn't sure about playing Voldemort and immediately told him, "You've got to do it." When Ralph saw the character design, he quickly got into the role, explaining that he saw Voldemort as (not human but) "the essence of evil." Even though Ralph does have a nose, he got into the role so well, he was frightening to watch even for Jason Isaacs., who its he was "terrified of him" whenever the directors called action.

9. Mike Newell Was The First Director To Treat The Main Cast As Adults

Mike Newell Rupert Grint Alan Rickman and Daniel Radcliffe in Goblet of Fire

Mike Newell was the third Harry Potter director and he only stayed for one film, The Goblet of Fire. Newell skillfully continued Cuarón's job of gradually turning Harry Potter into darker, more mature movies. The Goblet of Fire sees Voldemort return and Cedric Diggory (Robert Pattinson) die, which Newell explains comes as a cold shower to Harry and his friends, as they realize they have now become adults tasked with confronting Voldemort: "Suddenly, you realize that this movie is not about life, it's about death."

Newell knew this revelation would come at the cost of Harry, Ron, and Hermione's childhoods, and he brought this into real life, treating Daniel Radcliffe and the rest of the young Harry Potter cast like adults, according to Matthew Lewis, which was a first for them in of film directors. Rupert Grint describes Newell as a very energetic man who was almost like a real Hogwarts character. He might not be wrong, as Newell broke a few ribs teaching James Phelps how to fight his twin brother.

Related: Harry Potter’s Reunion Will Make You Love The Movies Even More

10. Daniel Radcliffe Had A Crush On Helena Bonham Carter

daniel radcliffe helena bonham carter harry potter bellatrix lestrange

When Helena Bonham Carter reunites with Dan on screen, she is quick to show him something he wrote her when they finished shooting for Harry Potter: "Dear HBC, it was a pleasure being your co-star and coaster, in the sense that I always ended up holding your coffee. I do love you. And I just wish I'd been born 10 years earlier. I might've been in with a chance." Dan is slightly embarrassed reading this, but Helena says she will always treasure that message, and that she has it in her toilet.