Omegaverse is an AU (alternate universe) in which males can get pregnant. It isn't always the most popular AU, but it is still used by others. In this system, there are three main roles: Alpha, Beta, and Omega.

First, at birth, the doctors will announce the gender (male or female). In some verses, you can pay to have a test done to determine whether the baby is an Alpha, Beta, or Omega. In others, you just have to wait until they are about 12-24 years old to find this out. So in a way, you have two genders. The male/female gender and the Alpha, Beta, Omega gender.

The Alphas are the more aggressive ones out of everyone. They are the larger and stronger ones, the dominant ones in bed. They are the males or females pumped full of testosterone. The females were different from the males though. While the males already have a penis, females don't. Everything is different for the Alpha females. They have a small chance of getting pregnant at all, but they can impregnate. Where the female's clitoris is, once she gets aroused, a retractable penis is there instead. Since she has a very small chance of actually conceiving a child, her womb would be smaller or not even there at all. In some verses, she does go through some stages in pregnancy to help her Omega. The hormones the Omega releases help the Alpha.

The female Alphas already small breasts would grow so she could help feed the newborn child. For males, it is a bit different. Alpha males can't have their breasts grow like the females, but they still help their Omega out. In almost all of the verses, there is a lot of semen being released. Some verses have knotting, which basically means the Alpha's penis enlarges at the base to lock inside the Omega, giving them a better chance at breeding and producing offspring. All Alphas have larger penises and are the ones to fight over an Omega.

Betas are the normal, everyday guy. They can still breed with other Betas, but they cannot breed with Omegas or get them pregnant. With a female and male Beta, they can reproduce that way. Sometimes even a female Alpha and a female Beta would be able to reproduce.

Omegas are the softer and more gentle of these roles. They are the nurturing parents who raise their children and they are the only ones in here who can get pregnant besides Beta females. The female Omegas use their systems as normal, getting pregnant that way and then nurturing the child as they should. But for the males, it is very different. All Omegas go through heats, it all depends on the author how often they go into heats. During this time, they are most fertile. But the pre-heat is what the males have to go through. Since they only have one hole, their rectum, that is also doubling as protection for the female parts.

During pre-heat, the parts start to grow after they empty their rectum completely. The reason they do it is so nothing gets stuck in the uterus. But Omegas are the smaller ones with less muscle and smaller penises if they are male. They love to take care of children and all that parenting stuff.

Heat is a time when the Omega is most fertile and ready to mate, or just hide away until the heat is over. If they have an Alpha mate, they will never leave their side unless they need to get their Omega food or water. Mainly, they have sex and then rest. They keep a watchful eye over their Omega, listening to them and caring for them. But in bed, they still are the dominant ones. If an Omega has no mate, that could be dangerous to even leave the house. They could get raped and forced into all of this, even if they protest and try to run. So they basically lock themselves in a room and use many toys to get through this.

A good part about this heat is that the Omega will self-lubricate, which means they only need to prep the Omega a bit more to have sex. During these heats, the hormones in an Omega go all crazy. A strong scent is released during the heats, causing the Alphas to smell it and chase after the Omega. If there is already an Alpha with that Omega, they will fight the other Alphas off. Some public buildings have small rooms in their basements for any Omegas who suddenly fall into the heat and need help. In some verses, there are pills to stop the heat from happening and some verses have washes that help cover the scent up. There is a pad-like item for the male Omegas to help stop the leaking from the lubrication when they are in public.

Pregnancy is about the same as in the real world. For Betas at least. For the Omegas, everything sort of changes and flips their world around especially one who has never had a child before. The male Omegas chest will grow to around an a-cup to help feed their child. The Omegas will most likely be happy about having a child. The Alpha will become more and more protective of not just their Omega but also the small child growing inside of the Omega.

It all depends on the setting of the story and how cruel or nice the Alpha could be. The Omega may build a nest in a closet or small room to mate there. They may even mate in public places or in a car or something. It really all depends on what you are writing or where you are at in the story.

A nest is usually a place where an Omega can be comfortable, whether if he is in heat or just having a bad day. It can be a closet or a couch, a small room, or a bed. It will usually be filled with soft things, the most smelling like his/her mate if they have one. It usually makes them feel comfortable at all times, even if they feel they are about to murder someone. With Omegas being the small fragile creatures they are, it can help them rest. As they get closer to their delivery date, they will most likely spend more and more time in their nest with their Alpha.

Betas can go into heats and ruts, but it all depends on their mate. If their mate is an alpha, they will go into heat. If their mate is an omega, they will have ruts. If their mate is another beta, they will have neither. Their bodies fill in the needs of the relationship, even though they don't have the exact same anatomy as alphas and omegas (I.E. knots and slick), it helps betas bond with their mates. This also applies to the sounds they make.