Demons

"Demons are not the evil dark entities in the sense you think they are. Oh yes, they are evil... But they are malicious familiars, strengthened by the negativity where they manifest. They prey upon the weak or sensitive, creating bonds to grow their own power and feed themselves. Once they are strong enough, they are more than happy to consume the soul of any magical being they can latch onto, wearing their flesh like a mask or warping their bodies to fit the demon's desire." - Octavia

Manifestation

Demons manifest in four different stages, depending on their strength.
Stage 1: The Unseen Voice Unlike their Familiar counterparts, something within a Demon prevents it from manifesting or roaming it's haunt. It is confined to a small space or lingering within an object. They are weaker than the weakest Familiar in a way, acting more like a disembodied consciousness or lingering malice. It is only capable of making itself heard until it is stronger. To gain strength, a demon will take a familiar bond with a sentient being. While the Demon is weak in it's ability to do anything for itself, it is strong enough to perform their duty as a Familiar, guiding the bonded soul in using magic.
A person who has bonded a demon is commonly referred to as a Warlock. Demons prefer to prey upon people who are vulnerable, whispering sweet promises of wealth, power, revenge, or any desire that the intended victim wishes to obtain. Once the bond is taken up, the Demon will continue to gaslight and promise to fulfill their partner's heart's desires, granting them the means to utilize magic as any other familiar would. The Demon grows stronger through these bonds like any other familiar, eventually progressing to stage 2.
Rarely, they will latch on to an animal or plant for lack of a proper pact-mate. However, if they have bonded a non sentient being, they will instead slowly leech the life from the body to strengthen itself. It will not kill the host, but instead work toward warping it. Non sentient bond-mates often live unnaturally long lives while the Demon latched to it skips straight to stage 4 when enough energy is gathered.

Stage 2: The Wisp The second stage of a Demon's manifestation is referred to as the Wisp stage. Through it's bond with the Warlock, it has grown strong enough to take a visible form. Often this form is a ball of light or smoke. They are still unable to interact much with the world, stronger Demons closer to their next stage are capable of shaping their amorphous form into different shapes, though still incorporeal and ghost like.
Stage 3: The Manifestation At the third stage a Demon is capable of taking a physical form, though not through the same means as a Familiar. Where familiars bend the energies of the flows around them, Demons utilize the physical materials around them. Dirt, wood, bone, rotting flesh, stone; anything can be used by a demon to create a construct like body for itself. The possessed pile of miscellany gives off a pale unearthly glowing smoke. Each Demon has their own preferred shapes and materials and early entry into this stage involves heavy experimentation to find it's own suitable body.
Stage 4: The Possession Once a Demon is strong enough it begins to search for a body to permanently inhabit. It will rarely choose it's bond mate as the victim of this, but in dire straights or when the bond mate mutually agrees it will. As mentioned before, demons will only select non sentient animals when desperate. Demons primarily choose creatures with strong magical connections and potential for inhibition, such as Faeries.
Possession first breaks any familiar bonds the victim possesses; the backlash of the forceful break eliminates extra resistances to it's influence as well as puts the victim's body into a brief state of shock. Once the demon envelops the victim with it's aethyr, it quickly seeps into the victim's body, mingling with their own energies. The victim is then mentally assaulted constantly as the demon seeks cracks in their defenses to breach.
The assault can last for up to a week. The victim is capable of conducting normal daily life during this time. Some victims may never realize what is going on, only hearing voices in their head encouraging their darkest thoughts and desires. The more in line with the Demon's own patterns, the more the victim falls into it's hold. Outwardly, the victim experiences physical changes, taking on traits of the demon's preferred form. A demon that prefers a body made of wood will cause bark to grow in place of the victims skin, one preferring flesh and bone may cause horns or fur to grow, and so on. The deeper into the hold, the more the victim's body begins to warp. The physical changes can be incredibly painful, further driving the victim into the demon's clutches. The process is complete when the demon is successful in taking over, either by shattering the soul of the victim, forcing the soul from the body, merging with the soul, or is itself expelled or defeated by the victim's will power.
When the soul is shattered or forced from the body, the demon takes full control of the body left behind, fully in possession of the memories of the body. A demon that has completely taken over a body can mimic the original soul well enough to fool even close friends and family. The demon also exerts total control over the state of the body, able to freely shift it's form to suit it's desires.
When a soul merges with the demon, the stronger of the two soul's traits are exhibited. This may show in a variety of ways, such as the demon being the majority of the new soul, with some traits of the old soul showing through; a calming of malice within the demon in a way, the old soul being majority of the new soul's traits with some of the demon's malice and traits showing, a balanced blend of the two, and so on.
When the demon is defeated, any number of things can happen. The demon could be destroyed entirely, bound as a familiar to the victim, locked away within the victim's body reverted to stage one without the ability to grow stronger again, expelled, bound to an object, etc. When a demon is defeated, it's warlock bond is often destroyed.

Type

Metaphysical, Demonic