First off. Krejin are human/dragon hybrids, they pretty much look like humans with dragon characteristics, such as scales, sharp teeth, some have wings, etc. They also have advanced physical strength, speed, agility, eyesight, and smell. They also heal faster. Powerful Krejin usually have more dragon characteristics.  No one knows how they originated, or where they originated from. they have hypotheses. but no evidence to back them up. All they know is that one day, 100 years ago, Krejin started being sighted near towns, and in forests. People became scared, and even though 90% of Krejin never hurt the human race, the military started training Enforcers. 

Fun fact: since Krejin run on the colder side, they love cuddling, and taking hot showers.

Enforcers are genetically modified humans, also known as 'mages' they have an affinity with magic, which allows them to control it. There are many forms of magic, but most is elemental magic, or subcategories of elemental magic. Very powerful Enforcers can even become the element they have an affinity with. For example a 'weaker' Enforcer who has an earth affinity, can make small/medium earth walls or make mini earthquakes. While a 'powerful' Enforcer can merge with the ground, and control it more efficiently, thus make larger walls, etc. After 10 years of service Enforcers are released from duty. When an Enforcer dies they turn to dust, literally, And it dissipates very quickly. They don't heal faster then regular humans with the exception of healing spells. Enforcers were created specifically to kill Krejin. If an Enforcer fails to kill a Krejin on purpose, they would be killed.

Fun fact: their eyes match their affinitys. Except when their discharged, then their eyes turn grey.

Lycanthopes/Lycans are another species that coexist in the world, they are very similar to werewolves, except they can turn into a wolf at any time and aren't forced into a shift on a full moon. The biggest difference between the two in this novel is that Lycans won't have physical differences, there will be alphas, betas, and omegas, but the rank is based purely on strength and bloodline. (Like how there are Five star General's, and Corprals, their both people, just their rank is different) Their both the exact same species. Alphas are usually born into leadership, and betas are middle rank and omegas are the lowest. They can also retain some wolf characteristics in there human forms, such as tails, claws, and ears. Etc. When their in human form, and their wolf pushes the boundaries of their human in order to shift, the humans eyes will brighten, this is the case for many were-creatures. Lycans are also pack animals, but they are much less likely to go rogue if they don't have a pack, or if their pack kicks them out. Like all were-people mentioned here, they have heightened senses. If you stare into a Lycans eyes, this is considered a challenge or threat. The only person that can do this without it being a threat, is the Lycans life partner. 

Fun fact: they love being pet in human and wolf form, but its extremely rude to pet them if you don't know them well. And is usually reserved for close friends/family, and their life partner.

Cynanthropes/Cynans are like Lycans, except that they have a dog breed instead of a wolf. They are much less pack oriented, though there are a few fairly large packs around the world, though they are much less common then wolf packs. They can have any breed of dog, and depending of the dog breed they have, when they shift they could be large or small. They are usually a bit larger then the original dog breed, and the dog breed also affects their personalities. Most Cynans are especially known for their sense of smell. Fun fact: most Cynans in their dog form love to play fetch, tug of war, etc.

Ailuran are were-cats, similar to the Cynans the Ailurans can have all different cat breeds, and each cat breed has different strengths, weaknesses, and personalities.  Though Ailurans are known for their stealth, agility, and hearing. They are normally loners, with the exception of lions and other pride cats. They can also shift of their own free will, and are only compelled to shift if they are experiencing large amounts of emotion. They can also retain some animal characteristics. Fun fact: They are very intuitive, so they are a great judge of character.

And other cool thing is whenever any of the creatures above (except Enforcers) feel a lot of emotion their eyes brighten, and change color.

That's all for now! If you have any questions please, feel free to ask!