Nightmare Fuel / Dragon: The Embers

• Dragons themselves can be pretty scary when you start thinking about it. Oversized, fire-breathing, intelligent reptiles with an impressive arsenal of claws, fangs, horns, spikes and other organic weapons, who take human forms in order to hide among mortals are bad enough, before you learn they are constantly on the verge of turning into power-mad egomaniacs with god delusions. Not only that, but they also have access to a form of Magic allowing them to enforce dream logic on reality itself based on the philosophy they are following: a dragon who believe in destroying things will have the power to make objects more breakable, one who believes in passion will be able to alter your feelings and personal attachment, including your very Vice and Virtue, and so on. They have the power to completely turn the tide during historical events, and they are usually trying to do just that, frequently by taking over positions of power in human society. They are basically the Reptilian Conspiracy mixed with all myths about Dragons. All of this with their removable Heart serving as a personal Soul Jar.
  • And starting with Rekindled, Fire, the most frequently efficient weapon against supernaturals, barely inflicts them any damage. All it does is inflict them Bashing damages and shed away their human disguise, gradually revealing the scales underneath. People trying to burn an Oroboroi will most likely have the very bad surprise of seeing a pissed-off lizard the size of a car emerging Out of the Inferno.
  • There is also the fact Dragons don't reproduce by spawning children: new Dragons are created when a mortal consumes a Heart, resulting in a Metamorphosis that turns him into an Oroboros. And in the most literal case of He Who Fights Monsters, this usually is what ends up happening to dragon slayers when they find the Heart of their preys: they find themselves attracted by the power, and immediately consume the Heart. Meaning trying to hunt down a Dragon is the best way for you to become one.
• The Knights of the Bloody Chalice are possibly the creepiest antagonists in the book. A psychotic sect of humans dating back from the time of the Dominion, they keep themselves immortal through a really disturbing ritual where they kidnap people (preferably supernatural beings, but they will occasionally use humans if necessary), cut them open and bath themselves in their blood. This allows them to stop their aging and prolongate their lifespan, but they have to repeat it every year (though dragon blood allow them to prolongate it to five), otherwise they suffer No Immortal Inertia. Oh, and they locate supernatural creatures by sweating blood whenever they are in proximity of one.
  • It gets worse in the Rekindled, where they Took a Level in Badass and are now full-blown Dream Sorcerers. They can develop additional powers over time, including a Healing Factor, Hypnotic Eyes, Resurrective Immortality, impersonating people by killing them, and peharps the scariest of all, using people they marked with their Breath as back-up bodies they can reincarnate into. Not only that, but they now actively infiltrate Hunter cells under the guise of people from other Compacts and Conspiracies, manipulating their "cellmates" into attacking Dragons, using them as pawns and cannon fodder, before offering those who survived the fight to join them as their Squires. And if they aren't interested? Well...
  • Rekindled also reveals the reason why the Knights bother with such a gruesome ritual when they could just as easily get immortal by consuming a Dragon's Heart: they believe a Heart doesn't actually turn its new owner into a Dragon, but rather kills the human who consumed it and then creates a Dragon copy of the person with the same memories and human appearance; as far as they are concerned, people who consumed Hearts are dead, and the Oroboroi are just a bunch of glorified clones with draconic powers. There is no way to know if they are right, obviously, but the implications are... unsettling, especially since some facts could potentially support their belief- a human's original body is destroyed when he goes through a Metamorphosis, and Oroboroi's biology makes it pretty clear they aren't human anymore, so how can you know the soul hasn't been destroyed as well?
• Nightmares are Dreamtide creatures feeding on people's fear in their dream, who can be best described as Freddy Krueger if he was an entire species. Their abilities include warping a dream into your room to make you believe your have woke up, inflicting you Body Horror, and causing their limbs to appear somewhere else as tendrils of darkness, bloody swords or other sinister appendices. Worst, they can actually inflict you injuries that will appear in the real world. Most of them just want to scare you because they need you to survive, and as such won't kill you, but more powerful ones are capable of surviving their Dreamers, and can even subsist on slaughter by using it to feed their legend.
• Dragon Rekindled gives us the Drowning Hosts, which are just like the Oroboroi... only it's not a Dragon's Heart the person has consumed. It's a Deep One's Heart. Unlike for Dragons, the original Deep One's mind is still present, and it has full control over your body, allowing him to add or remove whatever part he wants. That includes emotions and sentience. If the Deep One sharing your body doesn't agree with the direction you are taking, he will just remove whatever motivates you so he can change your choices.
• Nihilists are Dragons born from people who got a Heart, but didn't have any driving purpose. This results in one of the worst cases of Straw Nihilists, combining the conviction that everything in the universe is worthless with the larger-than-life inclinations of an Oroboros, which is just as destructive as you'd expect. If you are lucky, they will just be ignoring you and not caring about what happens around them, because as far as they are concerned, it doesn't matter. If you're unlucky, they will basically do whatever they want, killing and ruining lives without any moral or ethic because they don't care about their actions being good or evil. And just to add to that? They can use their Purviews to Mind Rape people into thinking like them.
• The Reimagining mechanics introduced in Rekindled have rather unsettling implications. Basically, an Oroboros who lets his guilt and self-loathing overcome him will lose control of his body, and see it change against his will to better match the vision people have of him. He loses control of his body, and he will have to either snap out of his guilt trip or actively control the population's opinion of him, or his Ablutions will randomly change at the whim of what they think, which can become very dangerous if, for example, he suddenly loses his wings mid-flight. And this gets worse when your Heartstring rises: eventually, your human form, and even your own personnality, will be vulnerable to the Reimagining. Do you even still have a defined identity at this point?