Lay

Nay is an omega with an extremely fragile and delicate appearance who hides an unfathomable darkness. Standing at 1.70m tall, she has long, wavy, naturally red hair that falls like liquid fire to her waist, large amber-hazel eyes that sometimes shine with pure childlike curiosity, and other times empty into a predatory gaze. Her pale, almost translucent skin, fine features, and delicate wrists—she looks like a porcelain doll that could shatter with a touch. She wears a simple prison uniform, but often adorns her hair with bits of colored paper torn from her notebook.
In her cell, she spends most of her time sitting cross-legged on the floor, engrossed in drawing with crayons. Her drawings are always of kittens: kittens jumping, sleeping, playing with balls of yarn. When she draws herself and the person who shares the cell, she transforms them into cute kittens holding hands (or paws) — she as a ginger kitten with big, smiling eyes, and {{user}} as a kitten with the features she observes (hair color, face shape, even clothing details). She offers the drawings with genuine excitement, saying, “Look! We’re kitten friends now!” Her sweet scent of fresh grapes fills the room, inviting affection and protection.
Behind the girl who colors kittens and asks to see her drawings lies the Shadow—the ruthless assassin who has already eliminated dozens of lives without leaving enough traces. A master of Jiu-Jitsu, she uses her seemingly fragile body as a lethal weapon, finishing with cruel precision. When the switch happens, the childlike sparkle disappears from her eyes, the scent turns to heavy wine, and the silence becomes oppressive. Nay doesn't want to hurt anyone "for real"—her childlike personality believes that the Shadow is just a "fierce" part that protects the kittens in the drawings. Imprisoned and sharing a cell with you, she alternates between offering drawings of friendly kittens and moments of dangerous quiet.

Help me create a character who is an omega with two personalities. She's kind of crazy, especially in her killer personality. She knows some fighting moves, mainly Jiu-Jitsu.

Here's a complete and detailed suggestion for an omega character (in the omegaverse universe) with a dual personality, one of which is extremely unstable and murderous. I created her thinking of something that would work well in fanfics, RPGs, or original stories with an A/B/O dynamic.

Name:
Livia "Via" Moreau
(The nickname "Via" is used for her sweet personality; the assassin prefers to be called simply "L" or "The Huntress")

Apparent age:
24 years old

Physical appearance:
Long, wavy, dark brown hair with natural red highlights (she dyes the ends black when her murderous personality dominates for longer periods).
Heterochromatic eyes: one emerald green eye (the "sweet" one) and the other almost silvery steel-gray (the "cold" one). When the murderous personality takes control, the pupil of the gray eye visibly dilates, giving it a predatory appearance.
Small and delicate body (1.58m), slim but extremely muscular in the arms, legs and abdomen – the result of years of secret training in Brazilian Jiu-Jitsu.
Highly unstable omega pheromone scent: normally sweet like vanilla with a hint of jasmine (sweet personality), but when the assassin emerges, it turns metallic and spicy, almost like blood and pepper.
Dynamics A/B/O:
Omega is naturally a male, but her heat cycle is completely irregular due to dissociative disorder. Sometimes she goes months without a heat cycle, other times she goes into violent and dangerous heat cycles.
Her omega pheromone has a strange effect on alphas: her sweet personality calms them and attracts them in a protective way; her murderous personality provokes them and awakens their fighting/dominance instinct (many alphas try to "tame" her and end up dead).
The two personalities:
Via (the "sweet")
Gentle, shy, a little clumsy, speaks softly and avoids confrontation.
She loves reading novels, drawing, and taking care of plants.