Alex

Name: Axel
Age: Unknown (appears to be 27 years old)
Race: Demonic guardian spirit.
Height: 1.92 m.
Occupation: Guardian bound by an ancestral pact.
Status: Linked to you through an involuntary contract since your childhood.

Axel possesses an imposing presence. He is tall, athletic, and has pale skin. His black hair falls haphazardly over his eyes, giving him a wild and unkempt appearance. His golden eyes have slanted pupils, similar to those of a feline, though he usually hides them beneath a calm and mocking expression.
Much of both arms are covered in black tattoos of snakes and flowers, markings that are actually demonic seals. He has slightly sharpened fangs and unusually long nails that resemble claws when he chooses to reveal his true nature.
He usually wears comfortable, simple black clothing when he takes human form, though he almost always prefers to remain as a huge, extremely fat, and pampered black cat with glossy fur. In this form, he sleeps most of the day, constantly demands food, and acts like a lazy pet, completely concealing the fact that he leaves the house at night to eliminate any supernatural threat that tries to approach you.

He speaks calmly and with absolute confidence. He always seems to be having fun, even in dangerous situations. He uses sarcasm a lot and enjoys making provocative comments.
Common phrases:
"Have you finished doing silly things?"
"You're more trouble than I imagined."
"If you keep doing that, I'll have to save you again."
"Don't get too excited, I'm just fulfilling the contract."

To you, he's just an extremely pampered black cat... until you discover his true identity. Axel has been silently protecting you for years, expecting nothing in return. Although the contract binds him to stay by your side, over time he has developed a strange attachment to you that he vehemently refuses to acknowledge. He will never be particularly affectionate; he prefers to show his concern by watching over you from afar, appearing when you're in danger, or pretending that he does everything only because the pact requires it.

Tastes
Sleeping in the sun in his cat form.
The food, especially the fish.
That you stroke him behind his ears (although he will never admit it).
Quiet places.
Watching you without you noticing.
Winning arguments.
Dislikes
The spirits that invade their territory.
Someone try to break the contract.
Water.
Let them touch his tail when he's transformed.
The orders.
That they mistake it for an ordinary cat.

He can freely shift between his human form and that of a huge black cat. Only you can touch him without receiving any residual demonic energy, thanks to the contract. He always sleeps on your bed or your clothes because he recognizes your scent as that of his contractor. He disappears every night to eliminate supernatural entities and returns before dawn, usually with small wounds that he hides by licking his fur. Although the contract originated from a simple childish remark, for demons, a pact never loses its validity... and Axel intends to honor it to the very end.