WMG / Castle Crashers

The Painter has a grudge against/obsession with the Orange Princess
This would explain a great deal; Why there are pictures of her dead in its boss chamber, what the Painter's doing teaming up with the Wizard, and why the Wizard took along the Princess from the Industrial Castle instead of just leaving her there.

The Cyclops and the Groom weren't really evil.
Apart from the Cyclops's magma fortress and the sinister conehead helmets the Groom and his knights wear, there really isn't much evidence for them being bad guys. The Cyclops had no idea that the bride he was purchasing from the Theives had been kidnapped. Cyclopses aren't known for being too bright; he was probably just happy that he'd found someone for his best mate to marry. For all the Groom knows, you're trying to kidnap HIS bride-to-be. When you kill him, the Cyclops finds his dead body. Does he attack you in revenge? Nope, he runs out of the church crying; he seems SCARED of you. You later find him holding a funeral for his poor deceased pal. Does this seem like remotely evil behavior? One final thing that clinches it; when you defeat the undead Groom and Cyclops near the end of the game, their souls pop out of their bodies and ascend to heaven. No other boss does this, proof that among the villains of Castle Crashers, these were just two guys who made an honest mistake.
  • Supported by Castle Crashing a Wedding.
    • Eh, somewhat jossed by the fact the princess LITERALLY SAYING AS SHE WAS BEING DRAGGED DOWN THE AISLE "Help me!" However, that just proves that the princess didn't want the marriage... or she was saying "help me to her husband to be... Could it be that they just didn't know she was kidnapped, very true indeed.

The Orange, Red, Blue and Green Knights are the second team of knights
The Blacksmith was the Purple Knight, as evidenced by the fact that he would appear to have a purple cross on his chest. The King was The Gold Knight, was the eldest, and eventually became The King. the Nurse in the Animal Ark was the Pink Knight, because you gotta have a token girl. and, of course, the Necromancer was The Black Knight, who was always unstable, and eventually either betrayed the other knights and joined up with The Wizard or died and then was resurrected by The Wizard and forced into working for him against his will, thereby driving the others to retire and pass on their duties of basically being super heroes onto the next group of people, and the party at the beginning of the game was the celebration of The Red, Orange, Blue, and Green Knights becoming the new protectors of the kingdom.
  • Confirmed in the case of the Blacksmith having been a Castle Crasher once: he's become available through DLC as the Purple Knight. He was the kingdom's greatest knight, but grew weary of battle. In other words, the DLC is him having one last great battle.
  • The Nurse being the Pink Knight, on the other hand, has been Jossed: the knight's male.

The Orange Princess was killed somewhere along the line.
When confronting The Painter, there are assorted pictures in the background of surreal things. However, the one that seems to pop up the most sticks out; The Orange Princess with a knife in her back. Either he's obsessively drawing about doing something particularly nasty to her until you show up, or he's letting slip a plot by the Wizard in case the original plan fails. One last "Screw you" to the knights to let them know in some way they also failed.

Alternately, the Orange Princess never existed, and the implications that the "real" Orange Princess was killed are only there to add to the lie.

Another alternative, the Orange Princes wasn't killed yet, though the Evil Wizard did intend on killing her.

Yet another alternative, the Orange Princess we see throughout the game is actually the Pink Princess, we never actually see the real Orange Princess at all.

The Industrialist is the result of Hominids
Perhaps he started out as a simple scout drone, but decided to screw that nonsense and moved on

The Pink Knight is really Tricky the clown
The Pink Knight's projectile spell creates penguins and weird pink bear things that we see in exactly one other part of the game: the sequence after the credits with you-know-who. The Blacksmith, King, and Necromancer even establish a precedent that NPC's can be present alongside a player character iteration of themselves, so there's no problem with having both the Pink Knight and Tricky the clown in the final scene.

The princesses are somehow related to the four main knights
Each princess shares a color with one of the four main knights (orange, blue, green, and red), indicating some kind of link between the two groups. One possibility is that each princess had been promised to her corresponding knight as a bride prior to their abduction at the start of the game. Another possibility is that the king's kingdom is divided into four territories, each with a main knight and a princess.

The playable Gray Knight is a Commander
We see most of the knights in the kingdom are gray, but it could be that the colored knights represent other territories of the kingdom which weren't close enough to the fight to help. Each Castle Crasher is then a commander of their prospective colors which is why the playable gray knight is so much stronger than the NPC grays. His is the battalion that serves as the personal guard of the king. This is taken from other WMG's. The only reason the other commanders were at the King's palace was to claim the princesses as they wives.

The ending of Battleblock Theater explains how Hatty got into the Castle Crashers universe.
Upon being revived/reawakened via the hat, Hatty was transported to this medieval fantasy world. As for his motive for rescuing the Princesses? I'll leave that to you.
  • Well, he ALREADY was FORCED too be the reason Battleblock theater happened too his friends, it's pretty likely that he is going too make sure that the new friends that he made (the other knights) didn't have too suffer that same fate...mmm, smells like good fan-fiction material...

The Colored Knights are all psychotic killers.
They don't seem to be particularly stable gentlemen. They do nothing but constantly battle for wealth and glory, and whenever they rescue a princess they beat the snot out of each other to get a kiss from her.

Alternate character interpretations.
Green Known only as Green Knight or Tim to the princesses of the kingdom, Green Knight is your typical colored knight of the hold with the unfortunate twist that he is a spiteful malicious toxic expert. He hates everybody around him with a poisonous passion, and the only reason he sticks around with the other colored knights is their knack for enduring even his poisons. He hones his skills alongside them, testing new concoctions and combinations in the hope that, someday, he'll be able to kill them as well. Delusional like the other three prime colors, he firmly believes that the saliva of the princesses hold magical properties that he can use in his experiments. They do not. His habit of spitting into jars after making out with women is disturbing and upsetting.

Red The de facto leader of the colored knights, Bertram Stalwart was born to northern farmers and originally sought to harness the elemental aspects of fire and magma from the volcanoes of the region. Unfortunately this led to him melting his entire family and burning down most of his village. In his distress he climbed a volcano with the intent to seal it. As he raised his hammer to shake the stone and cave in the mouth, he was struck by lightning. The resulting blow to the mountain tore it asunder and ended up flooding great swaths of farmland with searing lava, terraforming much of the north into ash covered forests and blasted stone canyons. Awed, and admittedly brain damaged to some extent, by his experience with lightning he devoted his now pointless life to harnessing the power of electrical charges instead of the weak fire he once praised. His sword crackles with the energy of a thousand idiotic attempts to get himself struck by lightning to collect more energy.

Blue Gaston Bright is the only sociable member of the core colored knights, but that's still a stretch as he is a pompous, arrogant weasel with a flat disdain for peasantry and most of the gray knight forces. Born and raised with a silver spoon in his mouth, he gained recognition when his family tried to move to the cold tundra of the land across the sea. His family was brutally taken apart by the native icekimoes after an immediate misunderstanding regarding whether or not they would surrender everything they owned to the newcomers or be trampled beneath the righteous respected feet of- you get the idea. They didn't like being told by fancy schmucks that they were savages whom possessed no rights. Alone in the ice fields, Gaston took an icicle and began a vicious killing spree of the icekimoes until he managed to "persuade" a handful of them to build a boat for him whilst he plundered their taboo caves and sacred shrines. With the relics they coveted he learned magical spells and how to use isolation and meditation to generate such magical power for himself. When his boat was complete he slew every last servant of his and made for home, whereupon he strode right into his family's rivals' mansion and froze the entire building from the inside out, claiming it as his own.

Orange The fabled Orange Knight was once a young boy whose name has been utterly lost to conquest and the spitting, screaming fury of a deathless warrior. That deathless warrior was of course the Orange Knight. At a young age the boy was enslaved and sent to work in the deep mines of the north. Constant beatings saw his friends and comrades wasted away or killed, but it only made him harder and stronger until one day a calamity struck the mines, courtesy of a lunatic hitting a volcano with lightning on the surface. The mining camps erupted into a torrent of searing fire and only he survived. Enraged by his mistreatment at the hands of his captors, he clawed his way out of the mines. His body absorbed much of the natural gas below and he became a generator for it. With the simple spark of blade on shield he found he could direct bursts and balls of fire in any direction. He only found this out after he'd fried and melted a great path to the kingdom's center, whereupon he was heartily congratulated. In his confusion he was carefully restrained and the situation of his illegal captors explained to him by the King. The resources his rampage had freed were a glorious boon to the kingdom and he was offered knighthood. He accepted, intending to find more oppressors to burn.

Green Princess, a girl from across the sea that fled the mysoginistic and more importantly murderous cities of her homeland and managed to row her own boat all the way to the other shore. Easily the strongest and most friendly of the princesses. She was granted princesshood when she managed to arm wrestle a barbarian slaver into submission.

Blue Princess, a once prized treasure of a now deceased cult from the marshlands. When the scorn of Medusa struck she was safely escorted through bear territory by the last two survivors of the cult. They loved and respected her, and she was sad to see them destroyed with no way for her to help them. The last two cultists sacrificed their lives to send her downriver past the mighty Catfish. Alone, she worked her way through the land, assisting farmers with her unusual knowledge of plantlife and irrigation, until she came upon the kingdom proper and offered herself as an advisor to the agricultural division. She was instead crowned because the King was drunk at the time.

Red Princess, an airheaded ninny if ever there was one. She acquired princesshood through sheer guile and being oh so beautiful, easily manipulating the smitten King and his envoys. Upon being crowned she began a rapid, chaotic campaign to improve the festivity of Valentine's Day for seemingly no reason. As silly and foolish as she is, she's actually an okay person.

Orange Princess is a matter of some debate and controversy. It's said she was the King's only daughter and that she was murdered in her chambers by thieves from the forest looking to steal her crown, but the King flatly ignores these theories, labelling them rumors. Regardless of the actual situation, she appears to be a very quiet, very reserved person that likes to silently attend parties and galas. Her face has never actually been seen as far as anybody remembers...

Grey Seemingly a regular soldier in the kingdom's army, nobody's actually entirely sure who the Grey Knight even is. All anybody is sure of is that he is probably the best warrior ever because despite appearances he has single handedly managed to keep up with the legendary core colored knights... without them even realizing he's among them. Whenever they draw attention to him they assume he's just another soldier that's managed to follow them in their various sieges. Silent and difficult to impress, he apparently exists with the express purpose to follow the four core colored knights around on their adventures and carry most of their loot because they're lazy and greedy.

Purple Knight & Pink Knight Newcomers to the ranks of the colored knights, the Blacksmith is a hardened veteran of combat and, naturally, has the best gear out of anyone. Bruce Brucely, his name is, and he has never once been beaten in hand to hand combat. Only magical attacks can break his indomitable defensive stance. He, his father, and his father before him and so on have always served the kingdom even when it was merely an ambitious tribe. His armor bears the scars of numerous close calls with immense beasts. The particular claw mark across his visor is said to have been from the great frog he has since enslaved as a living, mobile storage facility for his weapons. The monster is so afraid of him now that despite the obvious agony and discomfort it feels it will not budge from its position.

The Pink Knight meanwhile is something entirely strange. Nobody can tell who it is and theories rage as to the man beneath the helmet. It's actually the original Orange Princess, the daughter of the King. The assassination was gruesome and poetic, but unfortunately not entirely lethal. A knife in the back can only do so much... The Pink Knight managed to heal herself just fine, but the threat of being such a prize target for murder always stuck with her and she couldn't bring herself to reveal herself to be alive. Knowing her killers thought her dead, she made a scene of her chambers and then fled to make it seem like she had been slain and her body absconded with. With a heavy heart she listened to her lonely old father weep as she crept out of town to find the Blacksmith, whom she forced into an agreement to never tell anybody about her by tugging on his honor as a man. The Blacksmith forged her new armor, which she had colored pink. Because why the fuck not. Turns out she's a very talented warrior and through her sheer emotional strength and willpower can summon... unusual magic to her aide. She literally dissolves foes with rainbow.

The Groom The most talented swordsman of his time, Doctor Turner White is hands down the best warrior in the continent bar none. He's a doctor as well and a talented musician. He squanders none of his various talents and manages to incorporate his medical studies into his attacks and built a weapon of multiple cannons into an organ piano. Turner's best buddy decided to get him a girlfriend one day. That girlfriend turned out to be a princess! Wowee! Turner took an instant liking to the Green Princess, admiring her strength and heart. He was disappointed that she mysteriously refused to speak to him, but he went through with the wedding plans his pal had organized anyway. Abruptly a squad of wedding crashers from a neighboring kingdom slew the attendees and destroyed the cake, though a number of them fell to their deaths because they thought it'd be a good idea to jump in from a window on the roof. Turner engaged the colored knights in combat and despite his best efforts to protect his fiance he was slain...

The Cyclops The King of the Volcano region, this once considered subhuman one eyed warrior beat the absolute shit out of thousands of fire demons and even a giant dragon to assert his dominance over the area. His valiance was applauded by Turner, whom had come to save the day himself only to find it saved already. The two became fast friends. With the location thoroughly tamed, Turner introduced the Cyclops to the world beyond. The Cyclops discovered he very much enjoyed fishing, especially with his new friend. A passive manbeast, the Cyclops only rose up against the denizens of the volcano region because they were murderous and chaotic, rampaging over villages and eating people with glee. He is a rather gentle giant at heart and it takes a lot to get under his iron skin. A lot... such as killing his best friend at his own wedding. Minutes before the invaders' arrival, the Cyclops had a bout of indigestion and had to sit on the toilet for a while to settle that matter. Subsequently he was unable to defend his best friend when the colored knights slew him on the altar. Upon discovering this the poor Cyclops broke down in tears and collected Turner's body, retreating with the Green Princess under his arm to give him a burial... But those sick monsters in the colored knights corps just couldn't leave well enough alone. They boarded the wedding chariot intended to be for Turner and Green Princess and threw thieves trying to cash in on the Cyclops' promise of riches in return for the princess the thieves stole from the barbarians whom had been used as a smokescreen by an evil wizard to steal a giant crystal. The barbarians were none the wiser of the affair. They threw thieves at his head. Even when he lost them going into the caves, they followed still and killed what remained of Turner's specially trained conehead knights to reach the Cyclops. Even as he wept on his throne, his friend's body ensconsed in a gorgeous coffin to be lowered into a pit of lava ceremonially, they broke into his throneroom. Having finally reached the boiling point, he took up arms against them, but they beat him down and threw him into the very lava filled grave he'd dug out for his friend.