After the last class, people bustled around to get to their dorms, go outside, study at the library, anything they wanted to do with their free time- Except for the Purebloods and Harry, of course. Harry hadn't realized just how many purebloods there were at Hogwarts until he walked into the classroom and found it nearly full. 

There was, of course, Ron, Malfoy, Parkinson, Zabini and Neville, but among those he didn't know were purebloods were Luna Lovegood, Theodore Nott, Astoria Greengrass and Gregory Goyle. Sure, Harry knew that Nott and Goyle were friends with that clique of purebloods, but for some reason he never made the assumption. 

Harry hovered awkwardly at the back of the room, not taking a seat. No one had noticed him until the professor- someone he'd never seen before- noticed him standing around awkwardly and spoke.

"Ah, Potter. Go ahead, take a seat within your name bracket."

Harry cleared his throat, taking a single step forward as everyone turned to stare at him. "But I'm not a Pureblood, professor...?"

"Professor Lauralee. And none the less, your family history means it's mandatory for you to take this class. Now, at your table please. L - T is that table right there."

Harry frowned as he looked at the table, where Luna, Malfoy, and Parkinson sat. He sighed, collapsing down at the table and doing his best to avoid looking at the students sitting across from him. They seemed to be doing the same.

"Some of you will not be staying in this class. We will be taking a quick test to determine if you have what's required. I will hand around small pieces of paper and a small needles. Please prick your fingers and smear your blood on the paper. Make sure you get enough."

Harry looked over at Ron, the two of them sharing a 'what the fuck' look. He knew Hogwarts was weird, but this was black-magic cult-like weird. 

None the less, he obeyed, watching as Malfoy and Parkinson did the same. "This is fucking weird," Parkinson whispered to Malfoy, who made a noise of acknowledgement.

"Definitely. Feels like some sort of hidden contract." Draco frowned, watching as his blood dripped down his thumb, letting it gather for a few moments before pressing his print into the paper. 

After everyone was done, the woman who was apparently professor Lauralee waved her wand and muttered a spell. The papers all glowed a weird bright light, absorbing into the blood and making it glow a soft blue color on everyone's pages. 

"Alright. Everyone say Cruor Ostendo and tap the page with your wand. If your page continues to glow, you'll remain seated. If it fades, you'll be asked to leave."

Harry prayed to whatever god was listening that his would fade. He didn't want to be involved in this pureblood cult bullshit. If Malfoy was weirded out by something pureblood, it had to be weird. 

Once he cast the spell, however, nothing changed. He cursed, looking over at Ron, who was frowning at his piece of paper. 

"Alright. If your blood has gone dim, please pack up your things and leave. Your schedules will be updated accordingly. The rest of you, stay seated. 

Harry looked in dismay as Ron and Neville stood, alongside Goyle, Nott and Greengrass. Ron mouthed 'sorry mate' as he slipped out, leaving himself, Luna, Malfoy, Parkinson, and Zabini. 

The three Slytherins outnumbered them. One Gryffindor, One Ravenclaw.

Zabini raised his hand. "Miss? Why exactly are we here? Why did our blood... Glow?"

"If your blood glowed, it means you're either an Alpha or an Omega. Those who's blood did not glow were Betas."

"What does that mean?"

She frowned. "Were you not taught the history of Wizards and Witches?"

"We kind of spend the last year and a half fighting a war, professor," Zabini retorted sarcastically. "Education wasn't our priority."

She sighed. "Well, I suppose I'll give you a very quick brief then. Over three thousand years ago, the magical world was nearly wiped out by a plague. In order to not go extinct, many wizards injected the women with a mix of werewolf and veela blood. This gave the wizards chance to survive by boosting fertility- nearly a 100% chance of conceiving, over a 75% chance of having twins, 62% change of triplets and 37% chance of quadruplets. However, when the women gave birth and the children grew into adults, they noticed... Changes. It turns out that the injection created a whole second set of genetics that created Alphas and Omegas. Omegas were women who had boosted fertility- not nearly as high as the originally injected, but still very high, and men, who gained the ability to get pregnant and grew wombs. Alphas were dominant men who's job was to impregnate and protect the omegas, since they were weak from constant pregnancy and birthing in order to repopulate. Alpha women are extremely rare, since women's genetics are recessive, but they're generally very protective over Omegas without the desire to impregnate them. They became brood-mothers, watching over the omegas and taking care of them when they fell ill. The other omegas looked up to them. Betas were the ones who didn't obtain any of these traits, and remained normal. It's extremely uncommon for Alphas and Omegas to still exist today, but with the pureblood lines being re-merged over the last few generations, we're seeing a few show up- You guys, for example. This is the largest class I've seen in decades."

Harry frowned. Men getting pregnant? It seemed impossible- Especially anatomically.

The professor seemingly read his mind because she spoke up again. "In today's genetics, the male omega's ability to get pregnant has fallen off except for when they go through heats- which are similar to female cats, where they feel the extreme desire to be bred or mated- though in todays day and age, male Omegas are extremely rare. Alphas go through ruts every six months where they feel extreme desire to breed an omega. Any questions so far?"

Luna raised her hand. "How do you tell if you're an Alpha or Omega?"

"There are several ways to tell. What they typically do is do this test, then expose the subject to omega heat pheromones. You can tell from the reaction whether they're an alpha or omega. Of course, if not tested, typically your first heat or rut will let you know, but for the protection of the students, Hogwarts has charms- one to stop said occasions, another to cancel out the pheromone emission. This specific room has been sectioned off so that the charms can be turned on and off at my will."

Draco raised his hand. "Professor, are all alphas attracted to all omegas and vice versa? Or is it selective?"

"Wonderful question, Draco. It used to be all, but as I said, it has mutated excessively over the generations- when Veela's were introduced to the mix, not just in blood but in relationships as well, their genetic loyalty to partners merged interestingly. While in general everyone will be interested to the opposite secondary gender, once a connection has been formed, they will only be interested in each other, to a point of fatal loyalty. There is much more to be taught, but of course, this is only the first day. As of right now, we just need to figure out who's an Alpha and who's an Omega."