There was always a certain indescribable joy and excitement that came with the arrival of each new "Harry Potter" book. But imagine if when diving into the latest in the series, you discovered you'd actually be in the next movie.

Such was the case for actor David Thewlis, who played werewolf teacher Remus Lupin. MTV News caught up with Thewlis at the opening of the "Harry Potter" exhibit in New York City on Monday night, where he recalled the moment in which he'd be part of the "Harry Potter" franchise even longer than he thought.

While the cast and crew knew the "Harry Potter" series "had a finite life" because, as Thewlis noted, author J.K. Rowling "always had the course of the story worked out in seven books" ("It wasn't like, 'Oh, she's written another one!'," he quipped) at the beginning of the journey, the actor didn't realize what a big role he would play in the beloved franchise.

"I didn't know I was going to be in so many of them because when I did 'The Prisoner of Azkaban,' Lupin leaves at the end and he's not in 'The Goblet of Fire.' It was only when 'The Order of the Phoenix' was published that I realized, 'Oh, I was going to have more work in [the series]'," Thewlis said, adding, "So, it was very nice."

Thewlis also eventually figured out that he'd made it further than so many characters in "Harry Potter" as he told MTV, "I made it to the end! Which is tricky in ['Harry Potter and the Deathly Hollows']."

Of course, as hardcore fans know all too well (non-Potter readers, there are SPOILERS AHEAD) Lupin's luck runs out by the very end of the series. Still, Thewlis jokingly gave Lupin fans a glimmer of hope when he kidded, "[The death scene] may have changed, you don't know. I might just get quite sick." If only.

Are you sad that it's the end of the line for the "Harry Potter" series or are you ready to say goodbye? Let us know in the comments and on Twitter!