Disney and Dreamworks: Let's make super-compatible characters!
Once upon a time, there were four teenagers who all wanted something more. One was a young Viking with a draconic best friend and a talent for not fitting in. One was a dreaming girl, locked in a tower, who yearned to know of the world outside. One was a hot-blooded princess who wished to escape the confines of the royal life. And one was a reckless winter spirit who only wanted someone to believe in him. If these four ever met, it would be the beginning of something wonderful...
There was one problem. None of them existed in the same universe.
Until the Internet got a hold of them...
Or, what happens when Friendly Fandoms goes to the next logical extreme and becomes a fandom in and of itself. Also known as The Big Four, ROTBTD is the crossover of the popular movies Tangled, Brave, How to Train Your Dragon, and Rise of the Guardians. It kicked off big on Tumblr in late 2012/early 2013, and has gained a sizable fanbase in and of itself.
This crossover contains examples of:
Action Girl: Rapunzel and Merida, of course. Usually more emphasized in Merida though.
Alternate Universe: Admittedly the only way this crossover would work. Notable AUs include a modern AU, a Hogwarts AU and a Rise of the Guardians-Universe AU, where Hiccup, Rapunzel and Merida are chosen as Guardians. Occasionally they're also seasonal spirits (see Nature Spirit, below).
Anachronism Stew: If the crossover involves the timeframes of the original movies, it would technically be impossible for the characters to meet. Well, half of them. Brave and How to Train Your Dragon roughly take place in the 10th to 12th century, Tangled is in the 1700s while Rise of the Guardians is set in modern day. Jack was said to have existed for three hundred years, however, so he was human during the early 18th century.
Badass Normal: Merida, out of the Big Four. Archery and a bit of swordplay (as well as sewing) are all she has. In comparison to Jack Frost's flight and ice powers, Rapunzel's healing hair (as few fans are likely to use her post-haircut state), and Hiccup's dragon-taming skills (with crossbow and short-range weapon training on the side).
Big Bad: Generally accepted to be Pitch, the Nightmare King, if they're not at Hogwarts.
The Dragon: Mother Gothel is usually his partner in crime.
Mor'du and the Green Death are also occasionally featured as antagonists, though much less frequently. But when it happens, there's more of a Big Bad Ensemble.
With the release of How to Train Your Dragon 2, Drago Bludvist is well on his way to becoming a big-name baddie due to how big a threat he is.
Blonde, Brunette, Redhead: Rapunzel, Hiccup, and Merida accordingly. Jack could count since he was a brunette when he was alive.
Depending on the Writer: Despite what this page might imply, the exact nature of the fandom varies wildly from person to person. Some fans are in it for shipping, others for pure friendship. Some limit it to the four leads while others meld entire movie casts. Some writers use alternate settings — like Hogwarts or the standard High School AU — to facilitate the stories; others shuffle timelines and motivations around to slot the movies together; and still others simply ignore any details that get in the way. There are no hard and fast rules. The appeal of the crossover is in character compatibility, everything else is fair game.
Fifth Ranger: Characters from other CGI-animated movies are often added to the group. Most notably, it appears that Queen Elsa and Mavis are on their way of becoming this. The latter was something of a Guest Star Party Member for the original group, and Elsa is popular especially since people started shipping her with Jack. Eugene might also tag along — a Smolder never hurts in a pinch.
Hostage for MacGuffin: Another popular fanon, often used in 'trailers' using the dialog from the Rise of the Guardians scene with Baby Tooth, is that Pitch will trade one or all of Jack's new friends for his staff (often Rapunzel, using her hostage situation in Tangled).
The Medic: Rapunzel's healing hair means that she's able to fill this role.
Nature Spirit: Some AUs build on Jack's Snow Day powers by dubbing him the Guardian of Winter and assigning the other three seasons to the other three heroes, sometimes after untimely deaths of their own. This tends to work out surprisingly well, as is par for the course with this crossover.
Rapunzel is quite consistently in charge of Spring, forobviousreasons, although she occasionally headlines as summer (which is when she was born). Merida and Hiccup play musical chairs with the Summer and Autumn positions, depending on the fan creating the particular AU. (There are good arguments for either arrangement.)