Scott Pilgrim vs. the World is a movie directed by Edgar Wright and based on the Scott Pilgrim comic book series by Bryan Lee O'Malley. The story follows the protagonist, Scott, who has to defeat his new girlfriend's seven evil exes if he wants to keep dating her. Most of the main characters are in their mid-twenties, and the books and movie are a fun coming-of-age story full of over-the-top video game references.
Upon first viewing, Scott and his new girlfriend Ramona might come across as an ideal match. Scott is clearly infatuated with Ramona from the moment he first sees her, and Ramona is definitely cool enough to keep up with Scott's aspirations to make his band famous. The two also seem to get along fairly well and have enough chemistry to keep their relationship going when they first officially meet. However, watching the Edgar Wright movie and reading the comics again as an adult is a totally different experience from following the story as a kid, teenager or even a young adult.
The reality is, Scott and Ramona are both terrible people. They both treat their partners horribly, and by getting together, they start to realize how toxic they both are and learn how to become better people. This is explored much more in the comics than in the film, which makes the character development in Scott Pilgrim vs. the World rather lacking.
Scott is clearly a bad person in the movie. He dates Knives, a 17-year-old high school student when he is 22 and essentially leads her on by using her as a rebound after his breakup with Envy Adams. He then starts to pursue Ramona and kisses her while he is still officially dating Knives, cheating on her, or as Ramona says in the movie, he "cheated on both of us."
Scott also stalks Ramona and pressures her into dating him when she's clearly not ready to enter another romantic relationship, as she's still recovering from her breakup with Gideon Graves. When Nega Scott confronts him in the movie, it is revealed that Nega Scott is actually a really nice person -- this is because he is the opposite of regular Scott, and regular Scott is a bad person.
While Scott's flaws are much more clear -- which is to be expected as he is the main character -- Ramona's flaws are definitely toned down in the movie. In the comics, it's emphasized how much Ramona cheats on her exes and jumps from city to city to escape her past. This can be seen with her relationships with Lucas Lee and Todd Ingram and potentially her relationships with the Katayanagi twins, as it is mentioned in both the movie and books that she dated them both at the same time.
However, one moment from the books that didn't make it into the movie is a chapter where Scott and Ramona have an argument, and Ramona ends up cheating on Scott with Roxie Richter. Although the two apparently only kiss, this is definitely a bad thing to do and still counts as cheating.
One of the main reasons why Ramona seems like a better person in the movie compared to Scott is because all of her mistakes and bad behavior are left in the past, while Scott continuously messes up his relationships during the events of the film. The scene where Gideon uses mind control over Ramona and Scott reveals that he was cheating on Knives with her also makes her come across as more of a victim. Ramona was obviously a bad person in the comics because she was cheating and not being respectful of other people at the same time as Scott.
Scott and Ramona deserve each other because they're both horrible people. This is the main message of the comic book series -- two terrible people get together and finally realize how bad they are by mirroring each other's behavior, then grow and promise to do better in the future. While this ending is somewhat reflected in the movie, it does not fully capture the moral of the story in the original comics. It could be argued that Scott Pilgrim vs. the World isn't a totally faithful adaptation of Bryan Lee O'Malley's story as a result of this, and, as many fans have already claimed, the books were definitely better.