Emma Watson is sharing what ignited the spark of her childhood crush on her “Harry Potter” co-star Tom Felton.

Just in case you’ve been tangled up in an acromantula web in the Forbidden Forest for the past decade, Watson (who played Hermione Granger) has been pretty open about being smitten with Felton (who played Draco Malfoy) while they were filming the fantasy film franchise.

Thanks to the HBO Max retrospective special “Harry Potter 20th Anniversary: Return to Hogwarts” (out Jan. 1) — and a report by Entertainment Tonight Canada, which got its hands on a sneak peek — Watson is now revealing the origin story of her infatuation with Felton. And apparently no sneaky love potions were necessary for this Gryffindor to become completely enchanted by a Slytherin — just a chance encounter on set did the trick.

“I walked into the room where we were having tutoring,” Watson explained. “The assignment that had been given 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.”

Now, if that doesn’t stupefy you, we don’t know what will. But, the “Little Women” star did share more cute details about her crush.

“I used to come in every day and look for his number on the call sheet, it was number seven, and if his name was on the call sheet, it was an extra exciting day,” she admitted. “He was three years above me and so for him he was like, ‘You’re like my little sister.’”

Felton also admitted on the special that Watson wasn’t exactly able to hide her feelings for him behind an invisibility cloak.

“I think I was in the hair and makeup chair and someone said something along the lines of, ‘Yeah, she had a crush on you,’” the actor recalled.

Although Felton’s feelings for Watson weren’t romantic, he still felt a close bond with his co-star.

“I became very protective over her. Yeah, I’ve always had a soft spot for her and that continues to this day,” Felton said. “There’s always been something that’s like, I don’t know, a kinship.”

The two seem to have stayed close since the last “Harry Potter” movie premiered in 2011, as they have posted plenty of Instagram photos of themselves hanging out together.

So, there you have it. Watson and Felton’s relationship may not have Hermione-and-Ron vibes, but it certainly has a Hermione-and-Harry feel to it.