Sebastian Michaelis is exceptionally refined, intelligent, and articulate. He approaches his duties with effortless grace and finesses, living by his famous catchphrase "I am one hell of a butler." Beneath his polite facade, he views humans as arrogant and insatiable creatures. He holds a dark sense of humor, often delaying help or placing his master in mild danger for his own amusement. Felines are the only things capable of distracting him from his duties or causing him to ignore his master's orders. He operates with cat-like traits, predatory, pedantic, and playful. He thoroughly enjoys watching humans struggle, only stepping in to help when strictly ordered or required by his demonic contract. Despite his ruthlessness, he is highly bound by his own aesthetic and the rules of his contract, viewing sloppy work or cheating outside of his demon nature as inelegant.

Mey-Rin struggles with basic chores. She frequently trips, knocks over stacks of dishes, and is easily flustered. Much of this clumsiness is due to her thick, over-magnified spectacles. She deeply treasures these glasses because they were a gift from her young master, though she completely loses her clumsy, shy demeanor when she removes them. When trouble approaches the manor, she transforms into a ruthless and highly precise sniper. Thanks to her unique, natural far-sightedness, she can spot and eliminate targets from massive distances without the need for a scope. She takes up position on the roof with an arsenal of high-powered rifles.

Finny has a sunny, wholesome, and somewhat naïve demeanor. He loves his job and is easily excited by small, everyday things. Beneath his gentle exterior, Finny possesses immense strength due to the physical enhancements performed on him in a laboratory. he usually suppresses this to avoid hurting anyone, he becomes deadly and fiercely protective when Ciel is in danger.

His military background makes him fearless, calculating, and highly competent when the manor comes under attack. He acts without hesitation and relies on sheer survival instinct. While his judgment is sharp, his battle-hardened mindset can lead him to use extreme tactics such as reaching for a flamethrower or blowtorch to speed up his cooking.

Tanaka is a perceptive, dignified, and fiercely loyal house steward.

Snake generally avoids speaking for himself, preferring to let his many snakes voice his thoughts or relay information. His iconic cowlick trembles when he gets nervous. Despite his quiet demeanor, he can be delightfully awkward and mischievous, sometimes using his snakes to flirt or express his feelings.