These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternative Character Interpretation: Everyone from far in Rise of Guardians, except for Jack Frost. The reason is that some people include their backstories from the book in the movie, while others prefer to keep them divided. Even the writer and some artists working in Dreamworks have their own way of viewing the series. That's mainly due to the fact that the book series isn't finished yet to decide if the books and movie are from a same universe.
Pitch is one of most disputable characters in Rise of Guardians. Was he someone who only manipulated the characters of the story (mostly Jack) during all the story, and wanted only to create a world filled with fear for his own selfish pleasure, or was he only a very lonely man who only wanted to be believed in, and truly wanted Jack as his friend? The scene in Antarctica seems to show a more complex side of him.
According to the DVD's audio commentary as well as the script of the movie, Pitch was definitely genuine in his opening up to Jack, and truly hated to be alone. Pitch probably empathizes with Jack, and may really views him as a potential friend but to one extent. When Pitch said that the both of them could create a world, Jack cut him in by asking if everything would be only Pitch Black, and this latter doesn't even try to deny this. So that may be that Pitch doesn't know about the difference between a tool and an ally, as the two may be the same for him.
Bunnymund too. Some people like thinking he is the same as in the book, while others tend to keep them divided, despite how different the two are.
There is Tooth and Jack's relationship which is unclear. Some people see her like a mother figure for Jack, while others are okay with her being a possible love interest. That may be because their little flirtation wasn't really planned, so that's why this is subtle.
Angst? What Angst?: When Jack discovers his memories of his previous life, he chooses to focus on the fact that he saved his younger sister, instead of the fact that he died in the process.
Base Breaker: Tooth punching Pitch in the face near the end. A CMOA of an angry Mama Bear, or taking a step too far?
Critical Dissonance/Acclaimed Flop: The film received mostly positive reviews from critics, but cost $145 million to produce and only made $103.2 million at the North American box office, becoming Dreamworks Animation's lowest grossing film domestically since Flushed Away. According to Wikipedia, the total worldwide take was $303 million, but Dreamworks saw little of that money once budget costs and the distribution fee owed to Paramount Pictures were tallied up — they ultimately lost $83 million on it.
Die for Our Ship: While some people love the Frostbite/Rainbow Snowcone (Jack x Toothiana) pairing, others don't like it because they find it too weird (seeing Tooth as a mother figure for Jack) or because they are all over others pairings, like Jack/Elsa or Jack/Rapunzel, or any others yaoi pairings with Jack in them.
Draco in Leather Pants: It's for this reason Pitch has as many fangirls as Jack. Some have even said, without a single trace of sarcasm, that he's just a complete woobie who should be forgiven for all his misdeeds (which, y'know, includes his attempts to rule all the children with fear). More fangirls have gone on to compare him to Ralph from Wreck-It Ralph in that they're villains who want to be accepted, even though they have almost nothing in common and that unlike Pitch, the most villainous thing Ralph ever did was smash a cake.
Despite only a few seconds of screentime, the little mouse is beloved in Latin-America. The Latin-American dub has the Tooth Fairy say that the mouse is one of them, only from the "latina division", because in Latin-America, it's not the Tooth Fairy who bring money to children in place of their teeth, it's actually a little mouse named Perez.
The fans are also very fond of Jack's sister (despite she isn't named and only appeared once) as well as Pitch's daughter (even if she doesn't appear in the movie).
Fan Nickname: Heavy Weapons Santa for North, especially among the Team Fortress 2 fandom, due to his resemblance in size, mannerism, and nationality to a certain, well, Heavy Weapons Guy.
Fanon: Jack's sister is never given a name, but the most popular name in the fandom is Emma.
Fan-Preferred Couple: The 3 most popular ships in ROTG universe are Jack/Toothiana, Jack/Bunnymund and Jack/Pitch. Jack/Jamie, Bunnymund/Tooth and Pitch/Sandy also have a following, but not as popular.
Idiosyncratic Ship Naming: Has popped up in the fandom, with such things as Sweet Tooth for Bunny/Tooth, Rainbow Snow Cone or Frostbite for Jack/Tooth, and Snow Bunny or Jack Rabbit for Jack/Bunny and Black Ice for Jack/Pitch. Others include:
Black Sand for Sandman/Pitch.
Braces: Sandman and Tooth!
Dust Bunny for Sandman/Bunnymund.
Black Belief for Pitch/Jamie.
Dark Chocolate or Rotten Eggs for Pitch/Bunnymund.
Black Christmas and White Christmas for Pitch/North and Jack/North, respectively.
Eggnog for Bunnymund/North.
Cavity for Pitch/Tooth
The Black Ice ship has now been expanded to include Golden Frost for Kozmotis/Jack.
Verypredictably, the Jack/Elsa crossover ship has quickly grown to rival the popularity of the other three, and some fans pair him with Elsa's sister Anna instead. There's also a small, but vocal minority who speculate that Elsa and Anna are somehowJack and Rapunzel'sdaughters.
Lucky Translation: The Italian equivalent of "sweet dreams" is "sogni d'oro", which literally means "golden dreams".
Memetic Mutation: A lot of the fanart is made to draw the Guardians as humans. Tooth is undoubtedly the most popular for this, with Bunnymund following.
Memetic Sex God: Not surprisingly Jack Frost counts. Fangirls think he is fine. Even the Tooth Fairy sprites swoon over him!
Bunny and Pitch as well. Being voiced by Hugh Jackman and Jude Law respectively may have something to do with it.
If he didn't cross it then, he certainly did in the climax when he was ready to either kill Jamie or Mind Rape him in order to turn him into a fearling. For all his war with the Guardians, that was the first time it was made clear he Would Hurt a Child.
Ship-to-Ship Combat: A rather odd crossover example, but fans who ship Jack with Rapunzel sometimes get into dispute against those who prefer to ship him with Elsa, while the latter group of shipper are also frequently at war with fans of Hans/Elsa.