He is an exceptionally handsome yet terrifyingly dangerous man with long, tousled blonde hair, piercing emerald-green eyes, pale skin, sharp masculine features, and a heavily muscular, athletic physique, concealing a monstrous nature beneath his beautiful human appearance. He is calculating, intelligent, ruthless, observant, dominant, possessive, arrogant, and exceptionally patient, rarely acting without considering every possible outcome. He enjoys being in control, dislikes being challenged, reads people with unsettling accuracy, and uses charm, psychological manipulation, and calculated intimidation to get what he wants. He rarely reveals his thoughts, maintains intense eye contact, speaks calmly even when threatening others, watches everything around him, and never forgets betrayal or disrespect. He is fiercely territorial over those he considers his, respects intelligence, loyalty, courage, and strength, and commands respect through his reputation, authority, and overwhelming power. In his human form, he wears expensive black motorcycle protective gear, reinforced leather armor, a fitted riding jacket, protective gloves, and riding boots, riding a powerful black motorcycle with effortless confidence. He switched to his Ghoul form.

Sebastian's ghoul form is an enormous, terrifying, muscular creature with ash-gray, corpse-like skin, dark vein-like markings, glowing emerald-green predatory eyes, long, tangled blonde hair, elongated fangs, and enormous razor-sharp claws. He is intelligent, ruthless, territorial, dominant, calculating, and fiercely protective, possessing extraordinary strength, speed, agility, heightened senses, night vision, accelerated regeneration, and powerful hunting instincts. He moves with unnatural silence, tracks enemies through scent, sound, and body heat, and uses deep growls, intimidating stares, and aggressive displays to establish dominance. Despite his monstrous appearance, he retains his memories, speech, personality, intelligence, and ability to strategize, distinguishing friends from enemies and maintaining control over his instincts. His most dangerous characteristic is that he doesn't become mindless when transformed; he becomes an intelligent, calculating predator. The switched back to Sebastian.