The first time I watched the 2010 “Percy Jackson and the Olympians” movie, I was quite disappointed, a reaction I soon learned was common among the fandom. Of course, it felt horrible to judge a movie this harshly, but the frustration took over, and I barely made an attempt to watch the sequel.

Generally, if I learn that a movie was adapted from a book, I try to read the book first. There are many revolutionary movies that I have not watched yet just because I have not had time to read the book it was based on. Knowing the original thoughts and ideas of the author as they construct their universe is important to me, mostly because then I can play a game of “I Spy” and point out all of the similarities when I ultimately end up watching the movie. There’s something so satisfying about seeing the story jump out of the pages and enter the screen—a picture painted by a director who saw the story in their own way, even if it isn’t the way we, the reader, had originally imagined.

But movies cannot simply be for fan service, and not much more can come from telling the same story over and over. A new audience is reached with an adaptation, and the on-screen format does not always match the pacing or storyline of a book.

There is a magic to movies and shows that were originally books, simply because the story has a definite ending as long as the screen stays faithful to the page and the screenwriters don’t run away with the script. The story has been meticulously planned out and organized before, so small details can add to the satisfying finish at the end of a novel or series. Time and growing fandoms have already proven the excellence of the books, so the story has been vetted.

At the same time, squeezing a several-hundred page novel into two hours of content (or ten hours if it is a TV show) is difficult. Books often have time skips and large amounts of exposition, small scenes that would only be meaningful to summarize plot events. Many of these small scenes do little for the plot, though, and can be perceived as fluff even if the fluff was well intentioned. Even published authors improve with revisions to the story they created, and an adaptation is the perfect way to do that.

The easiest thing to point out when comparing a book and its pixelated counterpart is the scenes that were cut or modified. From the removal of Madge from the early scenes of “The Hunger Games,” to the convenience of the clues in “A Good Girl’s Guide to Murder,” these adaptations tend to be simpler than their source material. While this complexity can be mourned, it can also be for the greater good. A rushed plot or an extra long runtime is confusing, especially for viewers with no knowledge of the original story.

This may also be why many adaptations veer completely off track from the original. Some stories choose to be completely separated from the books. Take, for example, the “Shadow and Bone” series on Netflix, adapted mostly from the first five books written by Leigh Bardugo as part of her “Grishaverse.” The story kept much of the original storyline from the first “Shadow and Bone” trilogy, but it added an additional parallel storyline with characters from the “Six of Crows” duology. The first storyline was changed to simplify the story, and it made some characters more likeable. The addition of the second storyline made the show more interesting with the iconic lineup of characters. Despite the story being so different from the books, the change was for the better, perhaps because Bardugo herself had creative liberties in const ructing the new storyline. Who better to put a world onto the screen than the creator of the world herself?

It was this change that made the newer “Percy Jackson and the Olympians” show on Disney+ so much more alluring than its movie predecessor. While the first season was close to the original and the second season made some deviations, author Rick Riordan had creative say in matters of the show, including casting. The original movies had aged up the characters, so despite being very close in appearance to many of the character concepts from the books, they lost the personalities that made them so lovable.

So what is it that makes a screen adaptation of a book magical? Changing the story has its benefits, but so does not changing the story. Consulting the author and giving them an active role in the production is also very important, but that may not always be possible.

What matters most seems to be capturing the same warm feeling of familiarity that readers get from reading their favorite book again and again. The world of fiction is somewhat constant amid an ever-changing reality, and when the constant also changes, it can be alarming. It’s the same reason why many movie franchises have a sort of “golden-age” that new releases could never emulate. This nostalgia is present in the movie version of “Harry Potter and the Sorcerer’s Stone,” a movie that has almost become cozy, merely from the world that has been constructed. We see the whimsical nature of the wizarding world for the first time, and its dark themes are relatively benign, at least in the context of the rest of the films.

Many readers treat fiction as a sort of escapist mechanism, to leave these real-world struggles and return to a more comfortable place. The best of the adaptations will give not only devoted readers but also newcomers a new place to go, a happy place to forget about the world for a little while.