Everyone knows that the book is better than the movie... most of the time. There are a few exceptions that have proven the old adage wrong, most notably in the young adult realm. YA literature has always been terrific fodder for movies; look no further than The Princess Bride or The Outsiders for proof. The trend continues to present day, with Love, Simon as a more recent example of a successful adaptation.

RELATED: 15 YA Adaptations In Development (And 15 Possibilities)

Sometimes the end result isn't as gripping or as moving as the source material, but we expect that. It's when the movie is surprisingly better than the book when we count ourselves shocked.

10 Better: The Mortal Instruments

The Mortal Instruments series by Cassandra Clare is an incredibly popular YA series, complete with loads of fan merchandise, subscription boxes and spin-offs. The series features demon hunters, vampires, all sorts of magic and plenty of red herring twists to keep readers hooked. It's also filled with cool rune tattoos that many fans purchase as temporary fashion statements or even make permanent.

The film version of the first book flopped so hard that it failed to launch the series. It was easy to see why, with its senseless plot, makes-no-sense villain with zero layers, and lack of the connection that made the books powerful in the first place.

9 Worse: Twilight

As eyeroll-inducing as the Twilight franchise is to many people, it does have its merits. It brought the YA adaptation wagon back around to Hollywood, paving the way for a lot of other books to make it to screen, and it was an example of a wildly successful underdog movie directed by a woman (who unfortunately was later canned from the cash cow).

RELATED: 21 Wild Fan Theories That Completely Change These YA Movies (By Making Too Much Sense)

The book series, however, is more painful to experience. While the films are more action-oriented, the books are filled with Bella's pining thoughts, which literally state that Edward is perfect multiple times. They're also filled with much more emotional and physical abuse that too many bat their eyes over, labeling it as "romance."

8 Better: The Fault In Our Stars

The film adaptation of The Fault in Our Stars wasn't a bad movie. It was emotional, funny and powerful, much like its source material. Ansel Elgort and Shailene Woodley were excellent in the movie, and it received mostly powerful reviews.

That's why it's so important that fans read the book by John Green, which is even more moving. From Hazel's "desperately lonely swing set" to that sweet conversation on the plane, Gus's argument with his parents about traveling to many of the heartbreaking moments the movie left out, it's an experience not to be missed. And as fabulous as Elgort and Woodley were, it's really hard to top the Hazel Grace and Gus we imagine while reading the book.

7 Worse: Miss Peregrine’s Home for Peculiar Children

There are a lot of things about the movie version of Miss Peregrine’s Home for Peculiar Children that aren't so great, like switching Emma and Olive's "peculiars" and changing their looks, which seemed unnecessary. Emma's character is much stronger in the book.

RELATED: 11 YA Movie Adaptations That Completely Flopped (And 9 Massive Hits)

Even so, Tim Burton's movie does bring the story to life a bit better. The beginning of the book is much harder to get into, between the main character's whining and his terrible best friend. Caring about a character is integral for audience connection. Eva Green almost made up for the muted character of Emma by spicing up Miss Peregrine, and the action was much easier to follow in the film.

6 Better: The Harry Potter Films

While the Harry Potter films were wildly successful, the books were filled to the brim with world-building. J.K. Rowling created an incredible universe so vast that fans still want to know what happened to the grandchildren of minor characters and tune in to Pottermore for their answers.

Had the films been made with all of their original source material in them, they would have been several hours each, but we audiences would have been privy to incredible things like the Weasleys blowing up the Dursley's chimney, Fred and George's swamp at Hogwarts and other magical events. We didn't even get to see them de-gnome the garden!

5 Worse: The Perks Of Being A Wallflower

Another film starring Emma Watson, The Perks of Being a Wallflower also starred a killer cast including Ezra Miller, Logan Lerman, Paul Rudd, Mae Whitman, and Nina Dobrev. It adapted its source material, which was a wonderful book, into something most audiences could connect with, giving Stephen Chbosky's work justice, but the added star power really made it sing.

RELATED: 20 YA Fan Castings Better Than What We Got

The book's style made it difficult to get everything Charlie was feeling fully expressed on film, and some key components like a scene in an abortion clinic and the poem should have been included, but many fans did prefer the film, giving it an 89% approval rating at Rotten Tomatoes.

4 Better: The Hunger Games

Between the shaky cam, the lack of explanation regarding Katniss's deceptive actions, the versions of Peeta and Gale audiences got and so many fan-favorite lines and scenes being cut, the end result of the original Hunger Games movie wasn't nearly as incredible as its source material.

Most agree that Jennifer Lawrence did Katniss justice, although many fans thought she should've been portrayed by a person of color, and each film in the series still remained enjoyable and popular. Some of the cut material would have definitely changed the rating, preventing many teens from being able to see the adaptations of the books they loved.

3 Worse: Divergent

The tragic story of Tris Prior was an inspiring series of events for many fans of the Divergent series, but it was told in a muddled format that was never clear about Tris's direction. That's not necessarily a bad thing, but the movie adaptation had much more clear focus, pinpointing the uniqueness of a person over their faction in a more successful way than author Veronica Roth. It's also just paced so much better, making it easier to follow along with Tris.

RELATED: 20 Characters YA Adaptations Want Everyone To Forget

Fans were also excited to see a movie that so equally represented women and men in roles that played to their strengths in a world without, or with less, sexism than we see in many adventure movies.

2 Better: Percy Jackson

Any fan who has read the Percy Jackson novels by Rick Riordan will tell you that the movie is NOT a Percy Jackson movie. It is a completely separate entity that features characters with the same names. That is where the similarities end.

Sure, it's a decent action and adventure story, but if you go in expecting to see what you've read, you'll be incredibly disappointed. Not only is one of the lead characters, Annabeth Chase, completely out of character, not resembling her source material's look or personality in the least, but some of the best moments, like the battle in the St. Louis Arch, were completely cut. The whole thing is a mess to fans who were expecting their favorite book to come to life on screen in a full series of films that never panned out.

1 Worse: A Monster Calls

Patrick Ness gave fans of his incredible allegorical work A Monster Calls a film that truly brought his book with the same name to life. Since he wrote both the book and the screenplay, it's a hard call to say which is better since both are such wonderful works dealing with trauma, grief, guilt, and loneliness. It's one of the few YA adaptations that is almost a word-for-word representation of its book, with a few changes.

The film just gives us raw guttural emotions, between Conor's actions and the monstrous depictions of destruction, that we have to go with it. It may be one of the most underrated YA films to date.

NEXT: 8 YA Adaptations Coming In 2019 (And 17 We Have To Wait For)