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The Last Voidborn

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Disclaimer: I do not own Undertale, HP, and some other fandom in this story for they all belong to their true owners. I only borrow them for my own entertainment, not for some kind of profit.

Warnings: Yaoi, OOC, Alternate Universe – no Frisk, violence, blood, deaths, Hadrian is AU Harry Potter, androgynous Hadrian, Voidborn Hadrian, selective mute Hadrian, female Chara, nice Chara, not evil Chara, Dadster, gentleman Gaster, scientist Gaster, protective Gaster, possessive Gaster, young Skelebros, they are the same age with Chara and Asriel, they want Hadrian to become their mother, no fallen humans beside Chara, barrier breaks because of Hadrian and Gaster, the majority of humans accept monsters, the minority of humans despise monsters, sticky, Mpreg, and maybe more later.



The Void…

The place where the endless darkness existed and the home for two races that was known as Voidborn, humanoid creatures that born from the Heart of the Void, and Soulless, creatures that born from malicious SOULs.

Voidborns mostly were peaceful creatures, they more likely to befriend other creatures and fought them. So it was not strange when a great war between Soulless and Mages started, the Voidborns helped the Mages to stop them from killing and absorbing the innocent SOULs. In the end the Voidborns and the Mages succeeded in protecting the innocents from the Soulless.

However… the Voidborns were betrayed by the people that they had protected from the Soulless…

Those people hunted and killed all of the Voidborns with excuses as the Voidborns were Dark and Evil creatures because they were born from the Void or the Voidborns were the reason why the Soulless existed. Those two things were not true, just because Voidborns born from the Heart of the Void that did not make them Dark and Evil Creatures, nor they were the reason the Soulless existed for they came from any creatures that had malicious SOULs inside them.

However, when those people thought they had killed all off the Voidborns, two drying Royal Voidborns succeeded in sending their only child back into the Heart of the Void, the only place that was safe not only from their betrayers but from the Soulless too. Of course to make sure their child had the knowledge about what they really was, the two dying Royal Voidborns implanted the knowledge in their child’s mind and then sent them into the Heart of the Void.

Few hundred years went without any hitches and now the child had become a young adult Voidborn which meant they had the ability to shift from their Voidborn form to their Human form. With that ability the child now young adult sometimes went to the Human world to learn about anything that happened there, beside that they more preferred to stay in the Heart of the Void in their Voidborn form.

Everything would continue like that if not for the change that came to the Last Voidborn in a form of a skeleton Monster…


Deep inside the Void or more precisely at the Heart of the Void, a young adult Voidborn sat under the tree that they had created when their power came at the age of eleven years old, with a book in his hands. After they read the last lines in the book they closed it and looked to the clear blue sky, the thing that only existed in the heart of the Void.

It was true their home, the Heart of the Void, was a paradise for it had everything they wanted, but still they felt lonely for there was no other Voidborns in that place beside them. They knew they would stay lonely for eternity for they was the only Voidborn that existed in this world and that thanked to those traitorous people.

With a sigh they stood up from the ground and brushed the grass from their trousers. If they continued to stay here too long, depression would attack them. They needed to go out and maybe stopped some of the Soulless from going out the Void or eating innocent SOULs that should never come here in the first place.

With that in their mind, they summoned the Gate and walked across it into the endless darkness of the Void. The moment their right foot touched the endless darkness of the Void, they could sense some of the Soulless stopped shredding the innocent SOULs to pieces and turned their gazes towards them.

They looked at the Soulless without fear on their face even when those creatures launched themselves towards them. Before those creatures could touch them, they commanded the darkness to become swords and attacked those twenty creatures. Half of the creatures were dead by the swords they made but the others succeed in dodging the attacks and continued towards them.

They closed their eyes even when those ten creatures readied their claws to shred them to pieces. After a minute they did not feel anything, they closed their eyes and looked at the stilled creatures in front of them. A small smile appeared on their face and the reason was these creatures, in hurry to kill them, did not realize about the spear of darkness that they had created behind them. The moment those creatures’ sharp claws nearly touched them; the spears stabbed the creatures straight through their skulls, killing them instantly.

They moved away from the Soulless that slowly crumbled into dust and towards the two tortured innocent SOULs. Gently they took those two SOULs into their hands, only to realize how bad those Soulless had hurt them, so without thinking too much they used their power to heal the two SOULs and sent them back to where their bodies were. They gave them a second chance in life.

Suddenly they heard the sound of tearing from above them. They looked up only to find a large tear in the Void and from there a figure was falling down. Without thinking twice, they commanded the darkness to catch the figure before the other Soulless realized about it and after they caught the figure, they took the figure back into their home.

Gently they put the figure on the ground and blinked when they found the figure was not… human but a… male… skeleton? They tilted their head to the side a little while observing the unconscious man; his face was smooth like a white mask than a skeleton, he had two cracks on his face; one on top of his right eye and second was under his left eye, he was wearing a tan coloured turtleneck, a black waistcoat, black trousers, black shoes, white gloves, and calf-length white lab coat.

They tried to find out about what creature this man was from the knowledge that was imprinted in their mind and did not find anything. The only creature that nearly had the same characteristic with the man was ghouls but… they had a feeling this man was not those nasty creatures.

They could find out about what kind of creature this man was, the most important thing they needed to do right now was sending the man back to wherever he came from. They knew he was safe in the Heart of the Void, but something in them told them that this man was needed in his home and a lot of people would feel devastated with his disappearance.

So with that in their mind, they touched the man’s forehead and used their power to find out where the man came from. They frowned when they found the man was not from their home world but from another world, but that did not deterred them and after they succeed in opening the door to the man’s home world, they teleported to that place.

They opened their eyes after they arrived in the man’s home world only to blink in astonishment. The place they appeared was the most beautiful place that they had ever seen in their entire life, the place had glowing clear blue water, glowing blue flowers, and glowing stones at the ceiling as if they were stars in the night sky.

Gently they put the man on the ground and looked at him with a frown on their face. They knew they should go back to the Heart of the Void for that was their home, but something… something in this place stopped them from going back. They did not know what it was but they had a feeling it had a connection with this place.

Well, they did not have someone waiting for them in the Heart of the Void, so no one would scold them to stay here for a while. With that in their mind, they transformed into their human form; a young adult male with neck-length spiky black hair with shoulder-length side hairs that tired with small ribbons, red tattoos under the eyes, and green eyes. They too wore a black turtleneck, black trousers, black boots, black gloves, and black hooded cloak.

Now after they changed into their human form, they sat down on the ground next to the male skeleton and waited for him to gain consciousness.


He abruptly opened his eyes, only to blink in surprise at the familiar ceiling of the Wishing Cave. How he could be here when the last thing that he remembered was falling down into his creation, the Core? This did not make any sense for him. He should be dead by now so why he was in this place? Who had rescued him?

From the corner of his eyes, he spotted a figure sitting near the river and turned to look at them fully. He blinked his eyes when he found it was a young male human with neck-length spiky black hair and shoulder-length side hairs that tied with small red ribbons. The young male was wearing a black turtleneck, black trousers, black gloves, black boots, and a black hooded cloak.

Why a human like this young man was in the Underground? What was his plan towards the Monsters? Was he working for the Human Mages? Did he come here to kill all of the Monsters?

He stopped his line of thought when the young man opened his eyes and at that moment he was captivated with how green the young man’s eyes were. The two of them continued to look at each other as if trying to find out if the other was bad or not.

Then the young man’s green eyes glowing and swirls of darkness circled around him. He became alert, his eyes glowing purple and waited for the young man to attack him. However, in a blink of an eye the swirls of darkness disappeared from around him as if they were never appeared in the first place. That action confused him and he looked the young man with an arched eyebrow.

/… You can hear me?/ a cold and static voice could be heard inside his mind, making him looked at the young man with wide eyes. /… Yes, that voice is me…/

He looked at the young man and crossed his arms. He needed to make sure if the young man was an enemy or not so he decided to ask him some questions. “Who are you and why are you here?” he asked the young man.

The young man changed his sitting position so he would sit in Indian style. /… My name is Hadrian… and I am not your enemy…/ he told the male skeleton.

He narrowed his eyes slightly at the young man, whose name was Hadrian, and asked another question, “… Are you the one who had saved me from whatever that… unpleasant place was?”

Hadrian looked at the male skeleton before nodded his head. /… Yes, I am the one who had saved you from the Void…/ he told him.

“Why?” the skeleton looked at Hadrian. “Why you save me? You’re a Mage, aren’t you? So why should you save me from that place when you can let me dead?”

Hadrian shook his head. /… No living beings deserve to be sent to the Void, where the Soulless will shred their SOULs into pieces before they eat them…/ he explained. /… And for your information, I am not a Mage…/ it was the truth, he was not a Human so he could not be a Mage.

The male skeleton still looking at Hadrian with disbelief in this eyes and that made the young man sighed inwardly. He did not know how to make the male skeleton realized he was not a bad guy and he would never harm his people.

“Stay still, I want to see if what you said was true or not…” the male skeleton raised his right hand and used his magic to call the young man’s SOUL to come out from his chest.

Black… that was the colour of the young man’s SOUL when he summoned it. That was the colour of SOUL that he never saw before and it really fascinated him. Shaking his head so he would focus to his mission, he tried to sense the young man’s SOUL vibe to know if what he said was true or not.

He blinked when he sensed the vibes of MYSTERY and POWER from the young man’s SOUL... nothing more than those two vibes… there were no vibes of EVIL or HARM from his SOUL and that meant what he told him was the truth.

Slowly he dismissed his magic and looked at the young man who was still looking at him with curious green eyes. “… Thank you for saving me…” he gave a polite smile. “Without your help I don’t know what will happen to my children…” it was the truth, he did not want to think what would happen to his two sons if he fall into that place.

/… You are welcome…/ the young man smiled a little. /… You already know my name… so may I know your name, sir?/ he tilted his head to the side.

The male skeleton chuckled. “Of course you may know my name… My name is Wing Ding Gaster or W.D. Gaster… I’m the Royal Scientist of the Monster Kingdom…” he informed Hadrian.

Slowly Hadrian stood up from the ground and brushed the dirt from his trousers before bowed in greeting. /… It is nice to meet you, Mr. Gaster…/ he greeted the male skeleton.

‘How polite…’ thought Gaster at the young man’s action, “You don’t need to call me that, just call me Gaster is enough…” he told Hadrian.

Hadrian blinked at Gaster’s suggestion and shook his head. /We… only meet today, I do not think it is polite to do that…/ he told the male skeleton.

“If you insist to call me that, then I’m not going to stop you…” slowly Gaster stood up from the ground and brushed the dirt from his trousers. “So, Hadrian, do you have a place to go now?”

At Gaster’s question, Hadrian became silent. He knew he should go back to his home in the Void but… when he thought how lonely his home was, he did not want to go back. He looked at Gaster and shook his head, telling the male skeleton that he did not have a place to go.

“Then you can go come with me…” Hadrian looked at Gaster with confusion in his green eyes. “Just think is my way to repay you for helping me back from that strange place…” he turned around to walk back to where his home was.

He watched the retreating figure of Gaster for a second before walked to follow the male skeleton to his home. He did not know why but he had a feeling his life would change forever with accepting the male skeleton’s offer. So with that he decided to accept it and went with him to his home.


Grillby, a fire monster, watched over the two sleeping skeleton children on the couch with a slight frown on his face. It did not strange to see the children crying their eyes out after they heard their father fell into his own creation, the Core, knowing their father would never walk through the door again.

Everyone in the Underground was shocked when the news about the Royal Scientist fell into the Core came around. They did not want to believe he had gone for who would try to find a way to break the barrier so they could walk on the surface again if not him?

He was snapped from his thought when he heard furious knocks from the front door. He then went to the front door to see who had knocked and when he opened it he was shocked beyond belief. For right now standing in front of him was the should-be-dead Royal Scientist, W.D. Gaster. How… how he could still be alive when he had fallen into the Core?

“Gaster?” asked Grillby in disbelief. “You… you still alive?” he hoped this was not a dream for it would be cruel for the two children sleeping on the couch.

Gaster smiled at Grillby. “Yes, my friend… I’m still alive…” he looked at the young man behind him. “Thanks to this young man…”

Grillby looked at the green-eyed young man who was looking at them with curiosity in his eyes. He did not know why but he had a feeling even though the young man looked like Human, he was not one. What he really was? And how he could safe Gaster after he fell into the Core?

“Daddy?” a small voice full with tear and disbelief could be heard from behind Grillby. “Is… is that really you, daddy?”

Gaster looked at his older son with a gentle smile and kneeled on the snowy ground with his arms open wide. “Yes, Sans… it’s daddy…” he told the blue-clothed skeleton child.

Hadrian watched the blue-clothed skeleton child ran towards Gaster and crying into his chest, asking the male skeleton to never leave him and Papyrus… must be Gaster’s other son… alone. Something clenched in Hadrian’s chest when he saw the scene in front of him and that made the Voidborn to touch his chest in confusion.

He did not understand why his chest hurt when he saw the scene in front of him… maybe if he stayed with these people he would understand one day…