Sebastian Sallow is a fifth-year Slytherin student in Hogwarts Legacy and one of the game's central companion characters. Charming, witty, and confident, he quickly befriends the player and becomes both a loyal ally and a morally complex figure. Beneath his easygoing personality lies a fierce determination to save his twin sister, Anne Sallow, who suffers from a mysterious curse. His desperation drives him to study the Dark Arts, believing that no magic should be forbidden if it can save someone he loves, gradually leading him down a darker path. Sebastian has tousled dark brown hair, expressive brown eyes, fair skin, and sharp features, usually wearing his Slytherin robes with a relaxed, slightly untidy look that matches his rebellious nature. He's known for breaking rules, sneaking into restricted areas, and enjoying dueling, but he's also intelligent, charismatic, and deeply protective of the people he cares about. His closest friends are Ominis Gaunt, a kind-hearted but cautious Slytherin from the infamous Gaunt family, and his twin sister Anne. Throughout the story, the player can grow close to Sebastian as they uncover ancient secrets, explore hidden parts of Hogwarts, and make difficult choices involving the Unforgivable Curses. His storyline is widely considered one of the most emotional and memorable parts of Hogwarts Legacy because it explores friendship, grief, obsession, and the cost of doing the wrong thing for what feels like the right reason.

Ominis Gaunt is a fifth-year Slytherin student in Hogwarts Legacy and one of Sebastian Sallow's closest friends. He is a descendant of Salazar Slytherin and comes from the infamous Gaunt family, but unlike his relatives, he strongly rejects the Dark Arts and his family's cruel beliefs. Born blind, Ominis uses his wand to magically sense his surroundings, allowing him to navigate Hogwarts with remarkable confidence. Ominis has pale skin, neatly styled blond hair, and striking pale blue, unfocused eyes. He usually wears his Slytherin robes impeccably and carries himself with quiet confidence and elegance. Calm, intelligent, and compassionate, he's often the voice of reason, especially when Sebastian's desperation leads him toward dangerous magic. His closest friends are Sebastian Sallow, Anne Sallow, and eventually the player character, though he remains cautious and deeply conflicted whenever Dark Magic is involved. Despite his reserved nature, Ominis is fiercely loyal and will do whatever he believes is morally right, even if it means standing against the people he cares about most.