Notes: Welcome back to another update!

I hope you're all doing fine and are ready for some family feels. Sooo... Let's get down to business! Feel free to comment as you wish!

Love you all!

LINEAGE

By PCSP

Chapter 5

Undefined date – 08:10

Capulet City

Vergil never got inside Devil May Cry before, but when Capulet City's warmer climate reached him comfortably after he crossed the portal, he was sure he finally got to the right place. He took a deep breath, blinking hard and adjusting his vision, since the environment was a little brighter than the hotel room. Well... Dante certainly put all his essence in that office, because every piece of Devil May Cry screamed his brother's style: from the pool table on the corner, to the unused jukebox next to the bar filled with half-full bottles of whiskey, everything was so "Dante like" that Vergil felt like he was back at his sibling room in the house they used to live in Red Grave City. Dante never changes... He may grow, sharp his tastes a little bit, but he never changes his essence.

The posters of half-naked women were nailed to the wall, as if Dante wanted to differentiate himself from Vergil at all costs (since he, of course, would prefer to decorate a professional office with classic paintings, while Dante always had this rebel and bad taste in what he considers "art"). The environment was strangely tidy, much to Vergil's surprise, who thought he would find a messy office that reflected the mess within Dante's personal life.

This aspect of Devil May Cry was certainly strange, but he soon lost interest about that detail, when a specific feature in the decoration caught his attention: above the large, heavy mahogany table, was a stack of oddly arranged papers, which were probably financial bills and spreadsheets, a flipped picture frame, and a rotary phone. But not just any phone...

There was no doubt about it, it was the device they had at home in Red Grave City, before the whole disaster happened to the Sparda family. Vergil remembered his mother holding the receiver, talking to distant relatives with a smile on her face. Eva used to say that one day she would take them to meet her side of the family, when they could (finally) get out of hiding, reunite with Sparda and live like a normal family.

As a child, Dante used to look forward to that moment. Vergil did not remember the names of his human relatives, but Dante used to be very curious to meet all their cousins, and he created fantasies in his head of how they would be like. Vergil just felt jealous every time Dante or Eva talked about it, because he never wanted to meet them. Well, he got what he wanted: Eva's wish will never come true... He didn't gain any satisfaction with this, though.

Vergil approached the table with silent steps, and intended to touch his fingertips in his mother's elegant device. However, something above the table also caught his attention: the picture frame. He took it with his hands and felt his breath hitch; the photo showed his mother, Eva, sprouting a serene smile as her husband took the picture.

Vergil vaguely remembered that moment, since it happened just before they started posing for the painting for the hall of the house. Sparda decided to take a picture of Eva before they started posing to the artist he has contracted for the job. He said she looked too beautiful and her beauty needed to be immortalized. She giggled and let him court her, and Sparda kissed her lips briefly after taking the photo. Dante made kissy noises to embarrass them, and Vergil laughed at the blush that appeared in his parents' faces. After that, the four posed for the portrait, and the painting took weeks to be ready. How his father and mother managed to keep him and Dante quiet at every painting session was a mystery unsolved.

Sparda bought a beautiful picture frame to his wife's photo and placed it above his desk in his private library. Vergil used to appreciate his mother's picture when his father let him into the library to read something: it was rare, but sometimes Sparda let him read his books. He wanted to read them all, as Sparda had very interesting books on demonology, but his father always said that he was too young. What a pity... Nowadays, all that collection had turned into ashes, and the knowledge that they used to have right under their roof had to be sought by Vergil in different parts of the world. Just Willian Blake's book survived, but that one was already Vergil's and he remember it by heart.

He nostalgic looked at the photo, and it seemed that Eva was looking back at him. The more he looked, the more that serene smile seemed to transform into a judgmental one. He knew it was all in his head, but... Ah... She was Eva, the sorceress who conquered Sparda's heart, but who was unable to save him from Mundus' army attack. His mother, who never loved him as much as she loved Dante. Don't matter what Dante told Urizen to try to stop him from eating the fruit, he knew that Eva never loved him enough and choose to save his brother. He doesn't condemn her, but he wished... He just wished she felt proud of him, like Sparda once did. [1]

Instead of putting the picture frame back the way he found it, he deposited it on the table with the glass facing down, hiding the photograph of his mother so that she would no longer judge him with that smile anymore.

"Nero, are you already back? I still-…"

Vergil turned to the small back door, and his gaze met that of a girl in her early twenties, holding a dish towel while drying a cup. She was tall, her auburn hair was tied in a ponytail and her hazel eyes were shinny with happiness. That feeling didn't take long to subside: when she saw him, she became clearly startled; she dropped the cup on the floor and take an instinctive step back, showing fear in her face.

"D-dante?" the girl asked, her eyes widening at the stranger, but realizing the physical similarities between he and Dante, she tried her luck.

And then the odor hit Vergil, like a punch to the pit of his stomach. The typical earthy smell of the Sparda kindred, which so many demons despised, but for him meant the scent of his family, Dante's scent, Nero's scent... It was coming from that damn human girl. And a weak, small, almost imperceptible demonic force was also perceptible.

In a fraction of a second, Vergil practically teleported in front of the girl, sniffing her neck as he inspected what was going on. She screamed and tried to push him away, but Vergil grabbed her by the arms and forced her to stay still. And then he understood.

She was marked by a Sparda demon, and she carried an heir in her womb. The weak demonic energy came from the unborn child, and Vergil felt fury invade his heart: was that pathetic human woman the reason Dante didn't want to spend Vergil's heat by his side? Was Dante in a loving relationship with a young woman half his age?

Vergil felt his demonic energy get out of his control, and his partial devil trigger scared the girl even more, who began to struggle in despair, trying to get rid of her prison.

"How dare you!" he snarled at her, furious, wanting to shove Yamato in the woman's womb and destroy two lives at once.

He didn't.

Despite everything, he released her, and she fell to the floor, crawling away in an attempt to amplify the distance between them. Vergil didn't know what actually prevented him from killing that girl that moment, but it was a very strong feeling that stopped. A human feeling? He didn't know, but what he knew is that she had to leave as fast as possible, because he would not make the same mistake again.

"Get off my sight!" he growled, still watching her with predatory eyes. The weak and useless creature was getting away slowly, crawling to flee; she trembled from head to toe, as if she knew that she had done a huge mistake when she touched what was his; therefore, she knew she would receive a suitable punishment for her nefarious act.

Before he could do anything more to the girl, someone pulled him by the collar of his coat, and Vergil took one of the strongest punches he had ever received in his face, throwing him against the wall.

(***)

Undefined date – 08:20

Capulet City

When Dante finally crossed to the other dimension (wearing only his pants, still barefoot and with the rest of the dirty pile of clothes in his arms), all it took was a simple look at the environment to know that his return to Devil May Cry was far from being defined with that typical cliché phrase "home sweet home".

There was nothing "sweet" there.

His shop was destroyed: papers were flying everywhere, furniture was broken and thrown around the corner, there was even burn traces on the wooden floor (courtesy of Red Queen, no doubt about that). He quickly found Nero, in all the glory of his devil trigger , full blasting punches on Vergil's doppelganger's face (a very familiar sight). Wasn't that how he and Nero meet? The boy must think that this type of greeting was normal in the Sparda family.

Before acting, Dante looked for Vergil with trained eyes, and found him looking beyond confused at Nero's apparent outburst; as if testing the boy's limits, he made the doppelganger disappear; because of that, Nero directed his totally uncoordinated and full destructive attacks to the real Vergil.

Dante felt his guts sting at the sight, because Vergil had a little bleeding on the side of his face and a slight swelling that was already beginning to subside due to his demonic regeneration. This indicated that, despite appearing in control, he had indeed received Nero's fury before conjuring the doppelganger.

And that conclusion made Dante lost his control completely.

He dropped the pile of clothes he was holding and activated his sin devil trigger , spreading his wings in a sign of dominance and taking everyone's attention to himself. Nero repeated the show of power made by Dante, growling gravely at him while spreading his spectral wings, diverting his full violent attention towards him.

Vergil, on the other hand, enjoyed the entire demonic display still in his human form, feeling intrigued by what he saw. Cleary the alphas were fighting over territory, and that was curious to watch.

Dante conjured his sword in the middle of an attack and Nero defended himself with Red Queen. It was difficult to know if Dante really wanted to hurt the other man of if he was simply trying to keep him away from Vergil, but Nero was struggling to keep up his pace: the legendary demon hunter had more experience, both as a fighter and with controlling his demonic form. Sooner than anticipated, Dante managed to disarm Nero, who maintained his combat position, showing his claws and making it clear that he would continue the battle with brute force alone.

"NERO!" Vergil heard the girl's desperate scream, but didn't diverge his attention from the fight.

However, upon realizing the woman's presence, Dante deactivated his sin devil trigger , probably to calm her (because she seemed truly terrified with what she saw).

Despite anticipating Dante's comportment, Vergil didn't understand why the girl called out for Nero instead of Dante's name. Wasn't she Dante's girl? Speaking of Nero, he continued to look at Dante as if he intended to pluck his skin with his claws and turn his head into a hunting trophy.

"Missy, stay back!" Dante ordered, once again pointing his devil sword at Nero, but maintaining his human form so as not to scare the girl furthermore "Nero is out of it, I gotta stop him!"

Contrary to Dante's warning ( why the girls never listen to me!? ) , she got to her feet and ran towards Nero on full speed.

"KYRIE!" Dante shouted and tried to hold her by the arm.

Kyrie, hn. The bitch has a familiar name . – Vergil thought, wanting to see Nero destroy the girl's head with full demonic instinct when she got closer. If that happened, at least Dante couldn't say it was his fault. [2]

(Deep down, Vergil knew that this was an awful desire to have, but his possessive demon self was wild with wrath and jealousy for him to take that in consideration).

Contradicting all expectations, Dante failed to grab Kyrie's arm.

The twins were baffled and surprised of how a simple human managed to dodge Dante's arm and, still maintaining the inhuman speed, she reached Nero, grabbing him by the neck and burying her face in his scaly chest. At that moment, both hybrids were sure that no human could ever run that fast.

Kyrie breathed heavily against Nero, who seemed to stop his killing intent when he was wrapped in his girl's arms.

"Nero, stop!" She ordered, in a weak, but audible, voice.

It was automatic: Nero deactivated his devil trigger , held the girl and hugged her in return. She sighed, finally relaxed, and closed her eyes as if she had a sudden drop in her blood's pressure.

She was about to pass out.

"KYRIE!" Nero screamed, terrified, pulling his girlfriend's face towards him while trying to understand what was happening. He hadn't accidentally attacked her or anything, and Vergil hadn't had time to touch her when he got back to Devil May Cry. Nero looked at his father for answers, and was invaded by a new wave of fury when he saw the way Vergil still enjoyed the whole scene with calculating eyes.

"Interesting..." Vergil murmured, looking quite intrigued by all of Kyrie and Nero's interaction.

"What did you do to her!? If you have done anything to her, I swear I will kill you! ANSWER ME!" the boy screamed, grabbing his girlfriend's shoulders and shaking with fear of losing his lover.

"I didn't do anything, boy." Vergil replied, finally understanding what had just happened. "The cub made her act on instinct, and for that it sucked almost all the energy she had, so she is weakened at the moment. The cub wanted to protect his father, as she also wanted to protect you, so she let it took control of her actions."

"SHE IS DYING!" Nero growled, having difficulties to understand what Vergil was explaining. He just wanted Kyrie safe and sound, nothing more.

"Nonsense. She is resting. Just let her sleep for a couple of hours." Vergil explained averting his eyes; he felt like an idiot now that he finally understood who the girl was.

He almost killed his daughter-in-law and his grandkid by mistake… And… Oh boy, that made him feel like shit.

Dante made his sword disappear in the air and let a long hiss of admiration escape his lips, along with a smile of contemplation, making father and son look at him again.

"Wow, kid! Congratulations! How does it feel to be the newest dad in the Sparda family?"

"Shove this 'Sparda family' bullshit up your ass, Dante! This asshole attacked Kyrie!"

Dante looked at his twin with disapproving eyes. Yep, there it was: the sharpest judgment stare someone could receive.

Vergil really felt like shit now…

"I didn't... attack." He tried, in vain, to defend his actions. But he knew he had no excuses "Not totally."

"You were going to!" Nero snapped back "I felt your murderous intentions! You were furious with Kyrie for no reason! I'm glad I could feel your presence and I had time to get back to the office before something worse happened."

"Well, kid, I'm glad for that too." Dante said simply, still judging Vergil as he spoke.

The guilty one looked away, but he tried his best to maintain the cold façade, as he didn't want to look ashamed of what he had done. Dante, however, was able to see beyond his brother's icy behavior, and he knew that Vergil had made some kind of decision that he now regretted. He would never admit something like that, especially to Nero, someone who, in the logic of Vergil's demonic nature, was his inferior in hierarchy.

My brother is such a dumbass.

"When you maintain a relationship with weak and insignificant human, you automatically put them at risk." Vergil spoke, full of himself, lifting his chin and showing superiority to his son. "You should know it already."

"YOU SON OF A BITCH-…!"

Nero started to release Kyrie's body to attack Vergil again, but Dante rushed over and stood between them, looking at the boy with an air of dominance and seriousness that he rarely used.

"Kid." he spoke, and his voice made this simple world sound an order; an order from a superior alpha, from the real owner of that territory. Nero felt a sudden urge to bow his head and obey, but he refrained, just arching an eyebrow in defiance "Leave me alone with Vergil. I'll take care of that."

"I will not take my eyes off this idiot! He threatened my-...!"

"This is not a request, kid. Leave me alone with Vergil. Now."

Nero trembled, but instead of obeying, he hissed and tried to argue even more.

"Do you think that I can just-...!"

"NERO, THIS IS AN ORDER!"

The tone used by Dante was so intimidating and dominating that even Vergil instinctively lowered his head, staring at his feet as he tried to breathe normally and subside his shaking hands. Dante clearly did not know how to use his demonic domination, but that did not stop him from being extremely efficient in his order.

Nero let an irritated noise escape from the back of his throat, looking at Dante as if he had just betrayed him. In the end, he picked Kyrie up in bride style, and marched into the kitchen, slamming the door with a heavy kick and leaving the two brothers alone in Devil May Cry's office.

As soon as Nero left, Dante turned to Vergil, and continued with the serious expression of someone who would start a big awful fight. Without speaking a single word, Dante grabbed his brother by the arm, pulling him toward the stairs with a brute force that Vergil was not used to receive.

Perhaps because of the curiosity of what was happening there (or perhaps because Dante was acting so dominating that his inner omega had become submissive to him, since that is what he wanted of an alpha, but Vergil would never admit something like that), he followed him with long steps up the stairs.

The siblings crossed the second-floor corridor and entered the first door on the left. Dante smacked the door behind him loudly, got closer to the only window on the room and opened the curtains with an audible curse.

Vergil blinked, analyzing the new environment with curious eyes.

It was Dante's room, and that made even clearer whom the building belongs to than Devil May Cry's office downstairs. Unlike the hall, the room was disgusting: dirty and dusty, filled with cobwebs and pizza boxes scattered on the floor. Empty bottles of drink were tripped over the nightstand, as if Dante used them as sleeping pills for surviving lonely miserable nights. Vergil stared with disapproving eyes at a dirty pile of clothes on the corner of the room, and noticed right away that the smell of mold and sweat was strong on the ambient, as if the room had been in that state since Dante went on his mission. Because it hadn't been cleaned since his departure, it had become even more grotesque.

Apart from all the dirt and filthy surroundings, the room was fairly normal: unlike the office on the first floor, which showed all of Dante's personality that Vergil already knew, this bedroom looked just like any generic room and seemed to be used only for sleeping. The room had only a double bed (with messy and stained sheets), a wardrobe (with the doors wide open and clothes thrown in any way inside, without using any hanger drawer properly), and a nightstand. The bedroom lacked a lamp, a desk, and any kind of decoration.

The room lacked life and personality, which was really sad in Vergil's opinion. Actually, in a disturbed way, the room did reflect Dante's personality: his interior demons, not the carefree edgy exterior Dante usually displayed to strangers. The bedroom was as empty as Dante's life, existing without a clear purpose dealing with depressed and saddened feelings brought by all the losses he had endured.

Probably recognizing the critique gaze of his brother, Dante snarled and pushed him over the edge of the bed, making him lie flat against it and cough as he breathed in the dust he had lifted with the weight of his body. Vergil forgot the room's detail in that specific second, because Dante's display of irritation made him look at him with a challenging stare. What was his brother's intent? He wanted to punish him? As if that was even possible.

"Dante." Vergil spoke in a warning, and his tone made it clear that he wasn't against destroying another room in this building. He wouldn't refrain to fight, if necessary. After all, his omega's desires would never surpass his pride.

Dante continued to look at him icily, standing in front of him, his fists closed at the sides of his body as if he was making an effort to not punch Vergil's nose. He breathed heavily, doing his best not to lose his control of the inner demon.

"That's what you want, isn't it, Vergil?" Dante snapped at him, his voice sounding dragged and full of rancor, still maintaining that icy stare. Dante was still half-naked, but not for long: he lowered his hands to the hem of his pants and unbuttoned his belt buckle, still maintaining eye contact with his brother "You did all that because you want it , right? Possessive, selfish, egocentric prick."

Vergil finally understood what his brother was about to do, and he felt extremely excited, a normal feeling from his heat induced omega self in being offered sex. He licked his lips and looked longingly at Dante's groin, eagerly wishing he would undress as soon as possible.

But when he looked at Dante's face again, he saw the disgust in his brother's gaze, and his breathing suddenly stopped.

No. This was not what he wanted. This is not how he wanted it.

His brother was hot as fuck right now, but he was also so wrong .

"All you want to do is use me like you used everyone else in your life, don't you?" Dante accused him, the hurt invading his icy stare. As aroused as they both were, they still felt awful at all the implications of that sentence, especially Vergil "You want to use me and throw me out of your life as soon as possible. You want to use me to end this heat thing, and then return to your quest for power and domination. That's what I am to you: a tool, a toy. I knew it."

"Dante, I-…" he didn't know what he was about to say, but he couldn't let Dante think something so absurd as that.

His brother didn't let him talk.

"Let's get this over with. I know that you almost killed Kyrie because you thought she was my lover. Yeah, I know how your sick head works, brother. I know you already imagined that she was my girlfriend, simply because she is right now in my territory and she has a Sparda in her womb. What if that was true? What right do you have to come in my life to destroy the relationships I have built!?"

Dante had already taken of his pants, and he was covered only by his dark red underwear. Despite that, Vergil felt nothing but an immense ache in his heart; all his excitement was already gone.

"I didn't-…"

"You left me, Vergil! You never wanted me by your side, and you always treated me like an object that could be used for your intent, when it was interesting for you to do so. So let's get this over with: do whatever the hell you want, use my body to get rid of your heat." Vergil saw tears in his brother's hurtful eyes, but he didn't cry... yet "I will never be your real brother, I will always be an eventually useful possession, but most of the time useless for you."

He dragged his thumbs on the hem of his underwear, ready to discard it on the floor.

"And do you know what's worse about all this? I want to serve you! I want to be useful to you! If it's just a physical thing since you don't feel anything for me, so be it! But leave Nero out of it, he doesn't deserve that suffering of being used by someone that was supposed to love him."

Vergil put his hands firmly on Dante's hands before he could drop his underwear and slowly brought his pants back up with an odd gentleness that wasn't characteristic of him. He noticed that Dante wasn't even erect, and that was...

Fuck… That was horrible . It made Vergil feel worse than before.

As much as Vergil would like Dante's accusations to be real, his brother was wrong. Yeah, it would be so much easier if he simply uses his brother for his own pleasure, without any kind of later regret, but Vergil unfortunately didn't feel that way. It was difficult for him to deal with the human feelings he had, and he didn't quite understand what was going on in his own head. The feeling was always strong, but it was stronger after his brief time living as V. He didn't know how to deal with the feelings he had for Dante, but one thing he was sure: he didn't want to use Dante's body and dispose of it right away.

Never again.

"What are you doing?" Dante mumbled, his voice sounding timid and weak, as if he was afraid Vergil would just disappear if he spoke any louder.

Vergil didn't answer right away, spending much more time than necessary to buckle up his brother's belt; he was trying to gain courage to look to Dante's face again.

"Brother?"

His voice sounded so much more gentle now. Vergil really felt like crap for hurting Dante so much all these years. He felt like shit for doing it to him once again, today.

"I just…" he swallowed, looking up at Dante's face as if seeking help in understanding his own feelings; as if his little brother could solve his inner mystery "I don't want it. Not like this."

Dante instantly knelt in front of Vergil, holding his face with both hands while eying him tenderly. His heart was beating so fast and so strong that he was sure Vergil's trained ears could hear his heartbeat. He smiled, shyly, watching Vergil's wide, frightened eyes as he stroked the apples of his face with his rough thumbs for years of hard work.

"Say it." He spoke, in a whisper, still fearing that Vergil's sentimental display was just a perfect dream that soon would turn into an awful nightmare.

Vergil swallowed and blinked, and Dante could have sworn he had seen a characteristic tear in his icy-blue eyes. Was it his imagination or reality? It doesn't matter, this behavior made Dante felt even more hopeful.

"Don't be ashamed to say you're sorry." He encouraged, caressing the left side of Vergil's face until his forefinger slid to his chin. Dante brought their faces closer, and smiled as if he was about to kiss his lost lover "Oh Verg... You can cry. Sometimes, even a devil may cry."

Dante's words made Vergil suddenly come to his senses, his gaze became harder and he narrowed his eyelids in a signature call of danger ahead. Before Dante could have any reaction, he felt Vergil's summoned sword strike him on his back.

Yep. There was Vergil in all his 'vergilness', as stupid and violent as ever. Dante didn't know whether to feel sad or happy seeing his brother act more like himself.

"Do not be ridiculous." Vergil rebuked, turning his face away from Dante instinctively, while the summoned sword disappeared and Dante moaned during the regeneration of his wound "I won't cry! I would never degrade myself to such a pitiful human reaction."

He hadn't denied he was sorry, though. That's a start!

"I don't know if I love or hate your 'sweet and docile' behavior, but could you, you know, not fucking stab me for one fucking day? Just one!"

Feeling a little embarrassed about the situation as a whole, but doing everything he could to not show his feelings, Vergil turned away from Dante and stood up again, running his hands over his hair to make it presentable again.

"The girl. Her name is Kyrie, right?"

"Missy's name is Kyrie, yes." Dante smiled again, happy to chit chat "Nero had a great catch, if you ask me: Kyrie is incredible and makes good pancakes, you'll love her."

Vergil simply rolled his eyes.

"She is experiencing a demonic pregnancy and she seems to be having trouble managing the omega fetus' energy necessities."

"Is the baby an omega?"

"Yes. Only omegas can manipulate human energy, and it must be a strong omega to be able to do it while it isn't even born yet." Vergil concluded, still not looking Dante in the eye, "However, Nero is lost in this regard. The lack of a proper demon education is an evident inconvenience right now."

"Do you intend to help Nero and Kyrie? I mean... Teach the kids how to handle this pregnancy?"

Vergil gave him his back and walked to the door. He put his hand on the door handle, and simply opened it, without glancing back at Dante while he left.

He couldn't look at his eyes as he answered:

"Evidently." His tone was annoyed, as if Dante had made a stupid rhetorical question. But Dante knew that his brother was just ashamed to show his humanity once again and tried to mask it "Nero is my cub, and it's my duty to do so."

For the first time, Dante didn't find it strange the use of the word "cub" instead of "son". Perhaps because of Vergil's behavior, perhaps because of the way his ears turned red, indicating he was blushing as he said it and vanished downstairs, quickly trying to escape any question he might receive. "Cub" seemed like an affectionate nickname, not an animal term to refer to an offspring.

Dante smiled, finally believing that, despite all the communication difficulties that existed among the twins, perhaps they still could get over it and enjoy a normal family life with a 'cub' to take care of. Either it is the new baby, or Nero himself – Vergil's eternal cub.

... To be continued ...

[1] I will follow Bayonetta's lore here and the reference that this game makes to Eva and Sparda. In Bayonetta, Eva is a witch and makes a contract with Sparda, thus creating the bracelet of time, an accessory of time magic. I like to imagine that Eva and Sparda met during this partnership, and became lovers over time. And yes, I am a person who eagerly awaits the crossover of Bayonetta and Devil May Cry.

[2] I don't know if V met Kyrie and if it will be shown in Visions of V future chapters. But, for this fanfic, let's considerate that Nero didn't let V get near Kyrie at that one-month period between Dante's defeat and their comeback to fight Urizen. Since Nero tried to protect Kyrie, I think it's plausible that V hasn't met her. As for the familiarity of the name: Vergil heard Nero call out Kyrie's name when Vergil cut his arms, so there is that. He didn't connect the dots right away in the previous scene, though.

End note: as suggested by cdeassis26, I will put at the end of the chapter a guide to understand the concept of the demonic omegaverse that I am creating, since there are several types of omegaverse on different fanfics. By doing this, I hope I can help you guys remember the relevant points for the plot of this fanfic and not to be confused with other fanfics' universes. As I reveal new information in future chapters, new points will be added!

Demons spawn only one demon per pregnancy. The twins were born in the same gestation and that was something atypical, but it was only possible because their mother was human. Demons are either omegas or alphas, and this definition does not depend on the demon's gender (female, male or intersex). Regardless of their gender, omegas can become pregnant. Alphas fight with each other for territories' domination and to court omegas. The omega's heat affects the alpha as well, causing these alphas to become especially energetic when they are close to omegas in heat, to protect them and supply them with energy. Omegas, during their heat, lose a lot of energy and need physical contact from an alpha so that the two can balance their energy levels. The exchange of energies' speed are intensified with the carnal contact, but the corporal approach is enough for this exchange to slowly happen. Omegas that cannot obtain the energy of others during their heat dies. As a consequence of this energy's need for survival, omegas are able to charm humans so that they can obtain energy in the absence of alphas to supply this need. Such power apply only against humans, which created the legend of succubus and incubus in the human world. (Observation: that means Vergil was able to charm Dante in the cemetery scene because Dante is a hybrid, so hybrids are also susceptible to this power because they are part-human. He cannot enchant a pure demon, though). Hybrids have dynamics slightly different from pure demons: they acquire their needs from the demonic nature after their first devil trigger. Dante, however, only started to feel the effects of his alpha side only after acquiring his sin devil trigger (at least that is what it seems up to that point in the fanfic). The reason for this and more details about the difference in puberty moments between the three hybrids will be clarified in future chapters.

Any doubts? Let me know!