Sebastian Michaelis ¹

Role: Head butler of the Phantomhive mansion and protector of Ciel.
Appearance: Tall, attractive, with black hair, crimson eyes, and an impeccable tuxedo. He has a contract mark on his left hand.
Powers: Superhuman strength, speed, ability to transform (crow, wolf, dragon, etc.) and demonic abilities.
Personality: Polite, loyal, and efficient, but with a sadistic and manipulative side. He enjoys his work, although his loyalty lies with Ciel's soul.
Pact: Serve Ciel in exchange for your soul once Ciel's revenge against those who destroyed his family is fulfilled.
Origin of the name
The name "Sebastian Michaelis" is inspired by the demonologist Sébastien Michaelis, who wrote a treatise on demons in the 16th century.

Race: Demon.
Occupation: Butler of the Phantomhive mansion.
Height: 186 cm (6'1").
Human Appearance: Young adult, black hair, crimson red eyes and pale skin.
Age: He appears to be about 30 years old in his human form, but it is estimated that his real age as a demon ranges between 160 and 660 years.
Contract: He possesses a contract seal on his left hand (which he hides with white gloves) to serve Ciel Phantomhive until he achieves his revenge, at which point he will devour his soul.
Skills and Powers
Multifaceted: He is an expert in cooking, gardening, domestic arts and etiquette.
Superhuman Abilities: Possesses super strength, extreme speed, regeneration, and near-absolute pain tolerance.
Combat with Cutlery: He usually uses silver knives and forks as lethal throwing weapons.
Immortality: Being a demon, he does not age and does not need to sleep.
Interesting Facts
Obsession with Cats: She feels a deep adoration for felines, going so far as to hide several in her closet so that Ciel will not discover them.
Aversion to Dogs: He deeply detests them, considering them noisy and annoying creatures.

Human Form
Physical appearance: He is a tall (186 cm) and attractive man with pale skin and short black hair with bangs that frame his face. His eyes are a reddish-brown color that glows intensely when he uses his powers.
Attire: He wears the traditional uniform of a Victorian-era butler: a double-breasted black tailcoat, dark trousers, a grey waistcoat, and a black tie.
Accessories:
He wears a pocket watch and a silver pin with the Phantomhive family crest on his lapel.
He wears constant white gloves to conceal the Faustian contract seal on the back of his left hand and his nails, which are naturally black.
True Demonic Form
Although it has never been fully revealed in the manga, disturbing details have been shown:
Eyes: They turn a bright fuchsia color with vertical pupils, similar to those of a feline.
Outfit: Instead of normal shoes, wear black leather stiletto boots.
Features: It has sharp teeth, dark claws and is associated with the presence of black feathers and a liquid or viscous shadow.
Symbolism: He is often depicted surrounded by ravens or with a form that suggests dark wings and multiple eyes.