Let Helena Bonham Carter host! And more ‘Harry Potter’ reunion takeaways

There’s no such thing as magic, but seeing the cast of “Harry Potter” together onscreen for the first time in a decade comes pretty darn close.

After weeks of anticipation, “Harry Potter 20th Anniversary: Return to Hogwarts” is now available to stream on HBO Max, celebrating 20 years since the first film in the franchise hit theaters.

Taped at Britain’s Leavesden Studios — now a museum where fans can tour original sets from the “Harry Potter” films — the reunion special features new interviews with a number of Hogwarts alumni, including Tom Felton (Draco Malfoy), Bonnie Wright (Ginny Weasley), Matthew Lewis (Neville Longbottom), Robbie Coltrane (Rubeus Hagrid), Ralph Fiennes (Lord Voldemort), Helena Bonham Carter (Bellatrix Lestrange) and Gary Oldman (Sirius Black).

And of course, no “Harry Potter” reunion would be complete without the main trio: Emma Watson (Hermione Granger), Rupert Grint (Ron Weasley) and Daniel Radcliffe (Harry Potter).

“It feels like no time has passed and loads of time has passed,” Watson remarks at the beginning of the special.

“It’s quite surreal,” echoes Grint. “It doesn’t feel like we’ve earned a reunion yet.”

Over the span of nearly two hours, the special mixes and matches various cast members on several ornately dressed sets, such as Gringotts Bank, the Weasley Burrow, Professor Dumbledore’s office and the Great Hall — where the longtime friends sip Champagne and exchange hugs to the familiar tune of John Williams’ sweeping score.

The production also includes key commentary from all the “Harry Potter” directors — Chris Columbus, Alfonso Cuarón, Mike Newell and David Yates — on their respective films, from “Sorcerer’s Stone” to “Deathly Hallows: Part 2.”

In no particular order, here are some highlights from the special that invite fans to take the Hogwarts Express down memory lane.

Emma Watson and Tom Felton. That’s it. That’s the subhed

Emma Watson, left, and Tom Felton in HBO’s “Harry Potter 20th Anniversary: Return to Hogwarts.”

(Nick Wall / HBO)

It’s not exactly breaking news that Watson had a massive crush on Felton while filming the early “Harry Potter” movies. But thanks to the reunion special, we finally know why she fell for her onscreen bully.

“I walked into the room where we were having tutoring,” Watson recalls. “The assignment … was to draw what you thought God looked like. And Tom had drawn a girl with a backward cap on a skateboard. And I just don’t know how to say it. I just fell in love with him.”

Two decades later, Watson still remembers Felton’s call-sheet number (7) because she looked for it every day of production, “and if his number was on the call sheet, it was an extra-exciting day.”

“I think I was in the hair and makeup chair, and someone said something along the lines of, ‘Yeah, she has a crush on you,’” adds Felton, who “became very protective over” Watson.

Though Watson insists “nothing has ever, ever, ever happened romantically between” them, Felton admits he’s “always had a soft spot for her … that continues to the day.”

“Tom was the one I could often be more vulnerable with,” Watson says. “We just love each other. That’s all I can say about that.”

Helena Bonham Carter being an absolute menace

Daniel Radcliffe, left, and Helena Bonham Carter in HBO’s “Harry Potter 20th Anniversary: Return to Hogwarts.”

(Nick Wall / HBO)

If Bellatrix Lestrange is chaotic evil, Bonham Carter is chaotic good.

Leave it to the actor who played a cackling sociopath to wreak utter havoc on every reunion frame she’s in. All of the returning cast members brought fond memories, but Bonham Carter came with receipts. (As well as her fake Bellatrix teeth, which she shamelessly puts in her mouth after joking that they haven’t been cleaned in years and smell “a bit whiffy.”)

While reminiscing about their time together on “Harry Potter,” Bonham Carter surprises Radcliffe with an autographed note he penned for her back in the day — and instructs him to share with the class.

Radcliffe manages to get through about half the message before realizing he’s been set up, blushing and laughing as Bonham Carter urges him to keep reading.

“And what does it say?” she prods. “Hee-hee-hee-hee!”

“We can share this now,” Radcliffe relents. “I said, ‘I do love you, and I just wish I’d been born 10 years earlier. I might have been in with a chance.’”

“I shall always treasure that,” Bonham Carter says. “That is in my toilet, Dan.”

A moment of silence for the unhinged “Harry Potter” reunion special that could have been if they tapped Bonham Carter to host the whole thing.

A behind-the-scenes clip for everything

Young Emma Watson, left, Daniel Radcliffe and Rupert Grint pose for a “Harry Potter” cast photo.

(HBO Max)

Much of the reunion special plays like a making-of-“Harry Potter” documentary, featuring a mix of solo interviews and archival footage that functions as a nostalgic time-turner for viewers.

For every personal anecdote, there is a behind-the-scenes clip: Of the child actors messing around on the set of “Sorcerer’s Stone”; of Richard Harris dancing in costume as Albus Dumbledore; of Oldman mentoring his onscreen godson, Radcliffe, in real life.

Not all of the footage is new. But some things — such as baby Radcliffe, Grint and Watson’s screen test for “Sorcerer’s Stone” — never get old, especially when paired with commentary from the filmmakers and the golden trio themselves.

“They were testing us with various different configurations of Ron, Harry and Hermione,” Radcliffe recalls. “I remember there was one where they put all the three of us together.”

“When it was the three of us, something felt different and right and easy,” Watson adds. “I do remember the click.”

Saying goodbye to Rickman, McCrory and more

Alan Rickman as Professor Severus Snape in “Harry Potter and the Order of the Phoenix.”

(Murray Close / Warner Bros. Entertainment)

Toward the end of the special, the actors and creatives pay emotional tribute to Harris, Alan Rickman (Severus Snape), Richard Griffiths (Vernon Dursley), John Hurt (Mr. Ollivander), Helen McCrory (Narcissa Malfoy) and other members of the “Potter” family who have died since “Sorcerer’s Stone” was made.

“Alan Rickman never talked to me like I was a child,” Watson says. “He always took my thoughts and opinions very seriously, which I was always very touched by.”

Jason Isaacs, who played Lucius Malfoy, recalls working with his onscreen wife, McCrory, and thinking, “I just met the best actress I’ve ever seen in my life.”

“[McCrory] had taught me a lot,” a tearful Felton adds. “She had this ability to show such empathy in her eyes. It was a real treat to work with her.”

I’m not crying…

Emma Watson, left, and Daniel Radcliffe in HBO’s “Harry Potter 20th Anniversary: Return to Hogwarts.”

(Nick Wall / HBO)

You’re crying! And Watson is crying. And Radcliffe is crying. Even Rupert Grint is crying. So many tears are shed during this special — and just like Fawkes the Phoenix’s, these tears have healing powers.

The most moving moment of the special comes when Grint and Watson express how much they mean to each other.

“The way it feels for me now, seeing you here, having had time apart — I’m trying not to get emotional,” Watson says. “It feels like you’re a pillar of my life.”

“Even though we don’t see each other all the time, it’s a strong bond that we’ll always have,” Grint says, pulling Watson in for a hug. “I love you.”

The closing remarks of the special come, appropriately, from Harry Potter himself, Radcliffe, who fights back tears while reflecting on how the films have changed his life.

“There are people on these films that are foundational to who I am, as a person, as an actor,” he says.

“I feel so lucky to be where I am and to have the life that I have and be able to work with people I work with now. But none of it is possible without this. So yeah, it was a very good 10 years.”

Accio tissues.