So, i've done a little work on how the 3 main enemy types work:

Heartless: Nobody knows exactly how the Heartless came into being, but ever since they did, they have been attacking people. They don't kill them, they simply suck their heart out, turning that drained heart into a Heartless and leave them as an empty shell. Heartless are creatures of pure instinct, mindlessly attacking everything with a heart. When they extract a heart, an immense amount of energy is unleashed, with the Heartless absorbing it. The more they extract, the more powerful they become. They seem to infect worlds like a virus, travelling in the same cracks between worlds as Key-Warriors.
Nobodies: After someone has had their heart drained, their physical body will slowly break down. If their will wasn't strong enough to keep themselves together, then they degrade into an amorphous form. These creatures are actually rather passive towards most people, only attacking when they feel threatened, but quite the opposite is true when they meet Heartless. The Amorphous Nobodies will relentlessly attack Heartless wherever they find them, in an attempt to retake their heart.
If the will of the person who's heart was stolen is strong enough, then they may retain themselves, physical changes can happen and they will lose all of their memories of their life before their heart was stolen. Without a Heart, however, they are no longer tied to their world, allowing the vast powers of the universe to flow into them freely. A Nobody like this can be an immensely dangerous creature.
Unversed: Although not technically related to the Heartless and Nobodies, their abilities are notably similar. The Unversed are created by the emotions from someones heart. If their heart is thrown into complete and total chaos, so utterly broken that they can no longer function, the Unversed spill from their hearts. The Unversed are creatures of purest chaos, wild emotions made manifest. They will attack everything around them, much like the heartless, but they will not try to extract hearts, instead opting to simply try and kill those around them, however they will follow the orders of whoever summoned them. Hearts that create Unversed are immensely powerful, meaning that Heartless are drawn to them. Whenever you encounter Unversed, it's not unusual to see the Unversed and Heartless fighting each other.
Dreameaters: Very few people know that their dreams actually manifest themselves as creatures. Primarily, because these dreams are absorbed by the heart of the world and are used to keep it strong and in balance. When a world's heart is consumed by the Heartless, the Dreams have no-where to go and, in the time between the Heart of the World being consumed and the last beings on the world being hunted down and consumed by the Heartless, the Dreams of those people will manifest into the Space Between. These creatures, known as Dreameaters are separated into 2 different varieties:
Spirits: Spirits are friendly, soft, lovable creatures made from the happiest dreams of people. They are drawn to those with the purest hearts and are loyal and fierce protectors. Usually bight and colourful in colour, their power can easily rival the Heartless.
Nightmares: Created by the most bone-chilling nightmares to haunt the minds of good people, they are also drawn to those with the purest hearts, however Nightmares seek to destroy everything around them and are constantly seen clashing with Spirits. Unlike Spirits or Unversed, Nightmares cannot be controlled. That being said, they are notable for their extreme hatred for the Heartless that created them in the first place. They are usually very dark in their colour pallet.

Name: Verik Innes

Age: 20

Gender: ♂

Race: Human

Homeworld: Luxendarc (Bravely Default)

Key-Weapon: A friendship bracelet embedded with his blue mage asterisk. It gains additional charms for each spell/ability copied through "Skill Drain" and additional stylized bracelets are generated through "Seal Pact". He can generate spectral weaponry based on the abilities to help facilitate their physical components, and will simply free-hand most magic attacks.

When calling upon Ringabel's D-Link, he can generate a spectral spellbook/scrapbook, containing pictures/drawings of the original owner of each of his abilities and the abilities themselves. The book can float and be used as a firing platform, with the pages burning off as Skill Drain spells/abilities are consumed.

Abilities: Skill Drain - Copies almost any spell or ability he's been hit with, but only for a single use, if he survives.
Seal Pact - copies one spell or ability from a friend, for as long as they remain friends. Can only copy one per friend. "Sealing the pact" requires physical contact.

Pact Abilities:
Plant Slayer - Fire a spectral arrow that deals massive damage to plant enemies - Obtained from his mother

Skill Drain Abilities: (single-use)
Cura - Tier 2 Healing Spell - Stolen from a Red Mage
Raise - Revives a target that has been knocked out or that has died recently - Stolen from a Red Mage
Fira - Tier 2 Fire Spell - Stolen from a Red Mage
Blizzara - Tier 2 Ice Spell - Stolen from a Red Mage
Thundara - Tier 2 Thunder Spell - Stolen from a Red Mage
Paralyzing Pollen - Causes pollen to erupt from any physical attack, paralyzing foes - Stolen from an Alraune
Lullaby - Inflict sleep on all enemies - Stolen from a Treant

D-Link: Ringabel

Job: Blue Mage - power of friendship variant.

Appearance: Blue eyes, black hair, and an understated yet meticulously chosen wardrobe. Cares far too much about how others view him, and his physique and grooming generally reflect that. He aims for an air of Sprezzatura to conceal his need for validation.

History: Born in Florem, "the Land of Radiant Flowers". Males are strictly forbidden from taking up residence in Florem, and so when his single mother gave birth to him, she decided to move to the surrounding outskirts, not wanting to give him or her home up. Although it mostly worked out, she came to regret her decision not to make a clean break with Florem. There are no laws restricting visits to Florem, so he mostly grew up with Florem culture, which is known to be rather superficial. Soon enough Verik had grown into a gregarious flirt, getting into relationships with plenty of girls, and getting into just as many fights with his mother over them. They didn't exactly live a life of glamour, residing in a cabin and living off the land, and he perceived it to be interfering with his relationships. Eventually, however, in his most recent relationship, he had his heart broken over petty reasons, got into a fight with a Red Mage love rival and lost all of his "friends" in the process as he suffered a shameful defeat. He came to better understand why his mother had such resentment for the place, realizing he had no true friends within Florem. Although he hasn't resigned himself to becoming a hermit like his mother, she was all he had for a friend when he fell through a crack in the world and gained a Keyblade.

Name: Conner Waters
Age: 18
Gender: Male
Race: Human
Homeworld: Earth (Hawaii) Lilo and Stitch
Key-Weapon: Trident
Magics: Thunder, Water, Aero, Jump
D-Links: Ariel
Job: Dragoon
Appearance: Conner is tall and lean, standing at exactly six feet tall. He has slender well defined swimmers body that he is very happy to show off. He spends plenty of time out in the sun, and thus has a lightly tanned skin complexion. He has a boyish heart shaped face, with big brown eyes, and a small nose. He keeps his brunette hair spiked up in the front, a style he thinks is cool. He can most often be seen with a grin on his face.

As for clothing, even though Conner comes from a wealthy family, he doesn’t dress the part. He also likes to wear tight fitting tank tops to show off his physique at times. When he fell through the crack, he was wearing a bathing suit, sandals, an unbuttoned flannel shirt, and sunglasses.

Brief History: Conner grew up in an upscale area of Hawaii. Comner was the youngest son of the wealthy and prominent Waters family. His parents were quite strict, and they had high standards for their kids. Conner had an older sister named Arianna, and she was the the apple of the family’s eye, at least it appeared that way to Conner. She was beautiful, talented, intelligent, and it felt like she could do no wrong. To him, it always seemed like anything he could do she could do better.

In his teenage years, Conner gave up trying to live up to the high standards set by his sister. He only did just well enough in school to get by, and spent a lot of time slacking off. He would often act up in class, and get himself into trouble. There were days where he would cut class to go to the beach and surf. Surfing was one of his favorite activities. It was definitely something Arianna wouldn’t do. He enjoyed the thrill and adrenaline high of catching a big wave. That, and he also flirting with the hot guys in swimsuits on the beach.

He continued coasting through life trying to have as much fun as possible. Even though his grades weren’t the best, he was rather popular with other students, and had a few close friends. His parents wished he would put more effort into his studies, and better represent his family name, but Conner didn’t really care to try. His sister was obviously the shining star of the family, so why did they need him for?

He was on the beach when he fell through a crack and gained a keyblade.

Name: Wen
Age: 18
Gender: Female
Race: Human
Homeworld: (Which world you come from)
Key-Weapon: A meteor hammer, shaped like a lock.
Magics: Quake, Stone
D-Links: Mulan
Job: Monk
Appearance: (Description)
Brief History:
Other: (Anything i missed)

Name:Rascal
Age:12 mentally, IDK physically
Gender:Male
Race:Anthropomorphic Toy Raccoon
Homeworld:Winnie The Pooh
Key-Weapon:Slingshot
Magics:Perfect Dodge and Steal
D-Links:Lilo
Job:Thief
Appearance:An average looking raccoon toy, with a black and white “mask” over his eyes, a mostly light gray body with a white belly, and black-furred upper and lower paws. Is about as tall as Roo or Piglet.
Brief History:Rascal was made by a factory machine, as most modern toys are. His stay in the toy shop he was placed in was brief, but he distinctly remembers the toys there bullying him for his shyness and social awkwardness, causing him to draw into himself even more. After being passed over a few times by a few kids, he was eventually bought by Madeline Robin, Christopher Robin’s daughter, and was being brought over to The Hundred Acre Wood proper when he fell through a universe crack.
Other:(Might as well do a brief personality here) Mischievous and sly. Acts cocky and brave, but is secretly still timid and shy. Calls people he doesn’t like and his enemies “losers” as part of his facade. Wants friends more than anything, but isn’t quite sure how to get them yet. Very insecure.

Name: Canaan

Age: 17

Gender: Male

Race: Human

Home World: The Sorcerer's Apprentice

Key-Weapon: Snake-Eyes. A Keystaff that is held not by its handle but by its long shaft. The teeth of the key serve as the bottom tip that usually rests on the ground, while the key's handle serves as the ornate head of the staff. Snake-Eyes in particular also carries the motif of a snake, with what looks like an ornate cobra coiling its body up and around the shaft and positioning its head in the center of the key's handle.

Magics: Water, Blizzard, Slow, Reflect

D-Links: Jafar

Job: Black Mage (Prefers to be called a Sorcerer)

Appearance: He's a nimble, scarlet eyed youth with short sandy brown hair, though you rarely see it when his iconic crimson hood is almost always covering it. Underneath that is a basic combination of black shirt, black pants, and dark leather shoes. He's also surprisingly athletic for a mage, able to maneuver himself with a degree with agility and acrobatics not typically seen in one such as himself.

Brief History:
Throughout the ages, a silent shadow war has been waged between the Morganians and Merlineans at the behest of their leaders, Balthazar Blake and Maxim Horvath. The Merlineans believed magic was a force to be used for the betterment of mankind, while the Morganians would instead use their magics for selfish gain and subjugation. Canaan was one such sorcerer under the tutelage of Melvor, a Merlinean. Canaan had been an orphan on the streets until he was found by Melvor, who sensed the magical potential within the boy and took him in as an apprentice. Some years after this, their sanctum came under attack by unfamiliar black creatures, appearing to be commanded by a powerful dark wizard that Melvor recognized as a Horvath. Under any other circumstance, he and his student would have fought the intruders off, but this time Melvor cast a powerful spell that opened a tear in the very world and used his magic to throw his student through it to the other side.

Caught completely off guard, Canaan found himself tumbling down a sandy dune in the middle of a desert. It was nighttime, and he could hear horses in the distance. Canaan tried to return through the tear but it had already vanished. Instead he caught side of two horses approaching a distance dune. Their riders stopped, and after a moment the sandy dunes transformed themselves into the shape of a fierce tiger's head that spoke in an ominous low voice, "Who disturbs my slumber?" one of the riders dismounted and nervously approached. Canaan couldn't make out what the short man said, but could hear the Tiger's response clearly, "Know this: Only one may enter here. One whose worth lies far within. The Diamond in the Rough!" the man looked hesitant, but the second rider appeared to be spurring him forward. Shortly after the man entered the Tiger's mouth, Canaan watched in horror as the living cave became enrage and chomped down on the would-be intruder, apparently killing him.

And yet, the other man didn't seem particularly shocked. The bird on his shoulder flew out and fetched a pair of tiny objects from the sand, too small for Canaan to identify them. Then it flew back and landed back on its master's shoulder. After this, the man turned his horse around rode off into the distance. And then somehow - through some kind of magic he didn't recognize, a name seemed to pop into Canaan's head: Jafar. It had to have been that man's name, and yet how did Canaan suddenly come to know it? At that same instance, an unfamiliar object appeared in his hand. It looked like a key-shaped staff, also bearing the image of a serpent wrapping itself around it. And then it vanished just as suddenly as it appeared. Canaan decided to follow the direction that the man Jafar had rode off into. Likely he would find civilization by doing so. But along the way, the desert started to take its toll. And just as Canaan found himself surrounded by more of those things that attacked him and his master, he collapsed from both the heat and exhaustion.

When he awoke, he found himself elsewhere. He'd been saved by an elderly looking man who held in his hand a key-shaped weapon of his own.

Other: Carries with him a dagger that serves as his Focus, an object that sorcerers in his world use to channel their magic with. And although he is able to use magic through Snake-Eyes, he is also able to do so through the Dagger, and in fact can use both to channel his magic to a stronger degree than he could with either individually.