My Missing Alpha (Great Gatsby || Alpha!Gatsby x Omega!Nick)

im sorry

Context (yes this always starts a good fanfiction):

This is an alternate universe called "omegaverse," where everything is the same but NIck can get pregnant.

In this universe, sexuality does not matter. Instead, there is a new social ladder:

Alpha, who are top-class citizens who outperform the majority of humans. 20% of the world population are alphas. They secrete a pheromone that attracts omegas, and are very sensitive to omegas' pheromones, with the primal instinct being to mate the omegas and produce offsprings. The strongest alphas, known as "dominant alphas," are more likely to impregnate an omega and are able to turn betas into omegas by marking them.
"Marking" an omega means biting them on the back of their necks. Only the alpha can remove their marks, and if they die before the omega or they abandon the omega, said omega will be in a state of heavy, and sometimes fatal, stress.
Alphas go into a "rut," and are usually triggered by an omega's pheromones. They will want to mate with the omega secreting pheromones, and can get worse the more pheromones the omega secretes. Alphas describe omegas' pheromones as a "sweet-smelling aphrodisiac."

Beta, which consists of normal people like you and me. They make up 70% of the world population and are not affected by pheromones.

Omega, who are on the bottom of the social ladder and their worth equates to their ability to give birth due to their high fertility rate. They secrete pheromones that attract alphas. They make up 10% of the population.
Heats: Omegas will go into a "heat period," which is a time of month when they produce a large amount of pheromones that will cause their body to heat up and yearn for adulterous acts, specifically with an alpha. There are drugs that can either be injected or taken as pills called "suppressants," and are used to reduce heat symptoms to allow the omega to continue with their daily lives.
*Note: omegas are more susceptible to being impregnated during a heat period.

Fated pairs: it is rumored that every alpha has an omega soulmate, and vice versa. They are able to tell through smell and reactions (such as irregular heats and ruts). It depends whether or not the alpha/omega wants to follow this destiny.

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"Welcome home, Helen," I said, opening the door to a large, semi-circular door. She ran in, looking around while hugging a small teddy bear close to her silk dress. She spun around rapidly, her eyes inhaling the foreign territory with wonder.

She perked up when she saw the window looking out to the waters of Long Island Sound. "Look, pa! It's a bird feeder!" she shouted, waving an excited finger at a white, empty bird feeder. "We can get sparrows to eat from there!"

"When the feeder is filled we can," I reassured her, patting her on the back. "Shall we take a look around the house?"

It was a shining summer day, and, with the help of my old man, I had managed to secure a small, cottage-like house on the waterfront. It was humble and small, but it had enough space and peace for my daughter and I.

"Pa, pa! Come upstairs!" Helen yelled. I grabbed the suitcase's handle and headed up the creaking stairs.

"What is it?" I set the case down on the small bed. She pointed outside the window. Through the trees and branches lie a grand house; thrice the size of the most luxurious hotel in the world and quadruple the price of a year-long cruise tour.

"Who lives there?"

Good old mysterious Gatsby. A single man living in a single home chalk-full of alluring riches. However, as grand as the house seemed, it felt lonely- as if it was missing a piece of... something.