The first thing you'll notice about the new Demon Blood is the return of the distinctive red colour. A throwback to the original series, the red area not only looks fantastic but signifies the section of the blank where Daiwa has included 3DX carbon.
Ichor is the blood of angels and demons. Ichor is gold for angels and black, viscous, thinner than blood, and totally opaque for demons.
It's BLACK, not red.
TL;DR: daemons usually have blood because the forms they take on have blood, but it's not something they "need" to have, they just often happen to.
Demon ichor was a combination of blood, fluids, organs, and other internal remains of a deceased demon. It was found in large pools on the first layer of the Nine Hells, Avernus, as that served as the main battleground of the Blood War, where many demons were regularly slain.
A half-demon was a being who had partial demon heritage, usually the child of a demon with a human. They would present characteristics from both sides of their heritage while being a unique being themselves.
The strongest technique facilitated by the Blood Demon Art is Gyutaro's Rotating Circular Slashes: Flying Blood Sickles.
The relationship between humans, daemons, and ghosts is similar. A person dies when his or her daemon dies, and a daemon dies when its person dies, but the third part of the person continues to exist and becomes a ghost.
It is uncertain when or how, or into what form, a dæmon is "born", but a baby's dæmon takes the form of a baby animal. When a person dies, their dæmon fades away like "atoms of smoke." Likewise, when a dæmon is killed, its human dies as well.
In the world of His Dark Materials, every human has a physical representative of their own soul called a daemon. They take the shape of an animal, usually of the opposite sex of the human, and accompany them at all times. These daemons can speak, though they usually only do so to their human companion.
The colors of arterial and venous blood are different. Oxygenated (arterial) blood is bright red, while dexoygenated (venous) blood is dark reddish-purple.
He is an unimaginably cruel, sadistic demon who takes delight in laying waste to any world he encounters.
Human blood is red because hemoglobin, which is carried in the blood and functions to transport oxygen, is iron-rich and red in color.
The “Ichor” of the ancient Greeks is blue. (Or, some say, maybe gold). Blue; the colour of the blood running through the veins of Greek Gods and of European royalty!
The color of a demon's eyes denotes their status and rank in Hell's hierarchy. Black-eyed demons are Supernatural's standard sort. The oldest, most powerful demons like Lilith and Alastair possess white eyes, while Princes of Hell all have the infamous yellow tint that John Winchester saw the night his wife died.
Unlike humans, Demons have more than one heart. The number of hearts varies, although upper-level demons have seven hearts.
Daemons tend to be creative, artistic creatures, sometimes appearing to be gifted with genius and sometimes cursed with madness. Some daemons have supernatural abilities such as telepathy or precognition. They are usually born to human parents.
A daemon is a talking, animal-shaped manifestation of a person's soul, tethered to a human counterpart. Humans and their daemons, essentially, are one.
The connection between a person and their daemon is so profoundly personal that touching someone else's daemon is deeply taboo. The taboo is pretty self-explanatory in light of the fact daemons are people's souls.
In the first season of House of The Dragon series, you can see the Targaryens speaking the language. Daemon and Rhaenyra both use and speak High Valyrian as a way of forming a deeper connection between them — as if the old language is their own special love language.
Daemons can talk; not just to their human, but to other people. When someone in this world is still a child, their daemon can continuously change into any animal—it's when a daemon settles into a final form that a person is considered to have come of age.
Usually, a person's daemon reflects their personality: for instance, a lot of servants have daemons shaped like dogs because they're obedient (which, uh, probably kinda classist), whereas witches — more on that in a second — who fly through the air on brooms typically have birds.
Demon Curse: Muzan places a curse on all demons that have assimilated his blood. If any demon divulges his last name "Kibutsuji" out loud, the curse activates, which causes their bodies to stop regenerating and allowing Muzan's cells inside the demon to take over and kill them, regardless of their original intent.
Pyrokinesis: Nezuko's Blood Demon Art allows her to generate and manipulate special demonic flames created from her blood that are pinkish in color. Nezuko can do this by igniting her blood or creating it from thin air.