In a society that favors Alphas and Omegas while looking down on Betas, He Buqiu has disguised herself as an Alpha ever since she presented as a Beta. As a result, she's never dated anyone. She thought she'd spend her whole life alone, but an accident changed the course she'd planned for herself...
That day, she found an Omega in heat.
Only later did He Buqiu learn that the Omega was her future sister-in-law, You Yiyan. She couldn't have been more mortified.
He Buqiu made a point of keeping her distance, but kept running into You Yiyan, who was always teasing her in subtle ways. Luckily, she couldn't smell pheromones, so it wasn't a big deal, until one careless moment when You Yiyan marked her...
Omegas can't mark Alphas, but they can mark Betas. The moment she was marked, He Buqiu's identity as a Beta was exposed.
She didn't have time to worry about being marked. All she could think about was asking You Yiyan to keep her secret. But to her surprise, You Yiyan made an outrageous demand.
He Buqiu had no choice but to remind this outrageous Omega, "You're my future sister-in-law."
Ever since presenting as an Omega, You Yiyan has had people trying to arrange a match for her. But she has no interest in the eldest son of the He family.
One day, she visits the He family, and her heat arrives without warning. Then someone carries her away.
Frightened and panicked, You Yiyan throws all her strength into kicking and punching the person holding her. Only after being tossed onto a bed and helplessly shedding tears does she get injected with a suppressant.
When her mind clears, she sees the person before her looking perfectly composed and free of any improper intent, with a bruised face. Only then does she realize what she did. The person isn't angry or annoyed, and sincerely apologizes to her before leaving without waiting for a response.
Later, she learns that the person is the He family's younger daughter, and an Alpha to boot. For some reason, she grows curious about He Buqiu, and then falls for her.
No matter how much she flirts, even releasing her pheromones, she can't make He Buqiu fall for her.
Then, one time, drunk at a social gathering and leaning on He Buqiu's shoulder, she sees the gland at the back of He Buqiu's neck and, in a haze, bites down. She didn't think it would matter, but somehow she accidentally succeeds in marking her.
He Buqiu is actually a Beta? No wonder she doesn't react to You Yiyan's pheromones at all.
Watching He Buqiu cover her gland, looking embarrassed, annoyed, and flustered, an idea comes to You Yiyan.
"Date me, and I'll keep your secret."
An original ABO setting, no side characters.
Theme: Look at things from another angle, and you'll find yourself seeing something different.