The Knight of Ruin(DxD)

Following Romonus unlocking his Demonic Energy, he made sure to keep it hidden for as long as possible. The way he could get away with it so easily was that this was a Devil Manor. The maids, butlers, and every servant used a form of Magic every moment of the day. 

There were wards to prevent misuse or damage, but what Romonus was doing was the same as a household spell so no special attention had been brought to him. At a year old, he was still being breastfed by Wet Nurses, but Venelana had cut the tap off. 

Her duties as the wife of Lord Gremory AKA Zeoticus often took up a large part of her day. She made as much time as she could for them, but more often than not it was maids who attended to their needs. 

As for Zeoticus, he rarely if ever spent more than a few minutes with them as being the Lord of a Household took up his entire time. Or, he was off fucking his giant harem as a large portion of the maids in this house were in his harem. 

Romonus had to say the man had good tastes as all of them were big and busty. They looked radically different, but that was common. And he often got breastfed by a couple of them which was fun. 

Romonus even got to see his older brother Sirzechs and his wife Grayfia Lucifuge which was sad. He had hoped like in some fanfics she was not his wife, but that was not the case. Sad days ahead, but Romonus was not about to betray his new brother by fucking his girl. 

However, late at night, he continued his 'training' where he got a few on how to control his Demonic Energy. Rias would sleep through the night once fed which let him do his work. 

In his time on Earth, he had read several stories, fanfics, and the like which had different training methods to master Mana, Qi, Chakra, Prana, and even Demon Magic so after a month of simply getting a feel for how to move it in his body, he began to work on his control of it outside it. 

Like usual, he snuck out of his crib and sat down on the couch. He got into his favorite Cultivation pose with his hands on his legs. He didn't close his eyes this time as he began to send out his Demonic Energy. 

He was trying to do the string method which he learned in a Harry Potter Fanfic. The way it worked was that you would try to form your Mana or in his case Demonic Energy into a string. You had to send it out further and further away while keeping the energy like a string. 

Harder than it sounded as then you had to control the flow of the first one when you made a second, or third, and so forth. Each consecutive stream would work your control and multitasking. 

Already he could send out his Energy, but he was having trouble turning it into a string. Instead of a string, he looked like a big red cloud that was coming from his body. He squinted his eyes as he focused on the energy in the cloud. 

He pictured it condensing, solidifying, and forming a string shape which started to work. The could began to fall into itself, but after several minutes the closer he got was a rope shape with cloudy parts of it. 

Thanks to being born of Venelana and Zeoticus two very powerful Devils he was born with massive reserves. Emptying them took a while, but when they recovered it was a little bigger than before. It took him over a week before he got the trick down and he got his Demonic Energy to form the string shape he wanted. 

But to keep it as a string he had to keep his energy flowing as he began to move it through the room. The room he and Rias shared was quite spacious, but the further he moved it the more energy it took. He still had more than enough to keep training. 

'This is just one string and controlling my energy perfectly is tricky. Though, this is good practice.' 

As for Rias she slept the night away not aware of what he was doing. He squinted his purple eyes as his string of energy moved to the end of the room where he wrapped it around a book on the shelf. 

He had read each one and they had only stories of Devil Kind and very little training information. The rest of it would be in the library which he was not yet allowed in there. For now, he was stuck with this method which he did not know if it was better or worse than what the Gremory Clan had. 

This borring way was the way he spent the big part of his night for most of his nights. Night after Night he would train in controlling his Energy better and it was working. Soon he graduated to 2 then 3, 4, 5, 6, until 7. 

The more he made the better he got at controlling their movements which was a great way to train in his control. Another interesting thing was that the older he got and by mixing that with his training method the more his power grew. Just having that was helping him a lot as by the time he was three years old he had managed to move up to 20.

He could form them into shapes, and move them faster. If he had to say so, his reserves were massive. But that was enough for him to feel proud of his accomplishments. 

He kept it on the down low as from what he saw from Rias, she was not expected to be doing anything yet. She was still a regular child who was coddled by their parents, brother, and servants. 

Even though he received the same care, since Rias was cuter she got more attention. He wasn't being ignored as their Father seemed to hold him in high regard. Since Sirzechs became Lucifer, he could not become the heir of the household. 

Now that he had two children one being male his heir was secured. But, now that they were both three, they had been assigned an instructor. They were taught kid stuff, how to read, write, do easy math, and some Devil History. 

Nothing about Wars, just how their race had been created and the history of the Gremory Clan. That was interesting to Romonus, but Rias just wanted to goof off. It seemed even his existence was not changing her personality, but he didn't care what she was like. 

She may be his twin, but he was here to have fun, cause change, and do whatever the fuck he wanted. For that, he needed more power which was why he never slacked off in his training. 

In his third year of life, he began to add light physical exercise to his training like running around the mansion until he was exhausted, doing small bits of calisthenics here and there, and more food. 

He was always hungry as he was always using up his Demonic Energy and was always on the move. Now that he was up and about he made his way to the library where he began to read up on several subjects. 

Devil History, Demonic Energy Control Methods, rituals, Magic Beasts, and herbology. From what he knew, Potions were a thing, but not as common as would be expected. If he could invent Potions for his personal use he could make big money to find his future experiments. 

He had many and if he wanted to cause big changes in this world he would have to be as mighty as he could be. 

---

Currently, Zeoticus was in his office working on the paperwork of finances, political reports, and more stuff he rather not do. He much rather spend time with his harem, his wife, or his children, but work took priority. 

Just as he was working, the door to his office opened and one of his maids walked in. One of the fine ladies of his harem makes him feel a way to destress. 

"Marcina, glad to have you." 

She could tell what he wanted, but before that, she had to say why she was there. 

"Before that, I thought it is prudent to inform you about your son Romonus." 

That snapped him out of his mood. 

"Is he ok?" 

"He is fine, but he is in the library reading." 

"Reading what if you know. Nursery rhymes, or picture books?" 

Marcina shook her head. 

"No, he is reading Ritual Books, Beastiaries, Herbology books, and geographical maps." 

That took him for a loop. 

"Huh? Why? Is he even reading?" 

She nodded. 

"When I noticed him in the library I asked myself that question. I walked over to ask him about his choice in reading and he said he had to. I didn't press him and came to you instead." 

Zeoticus hummed as he touched his chin. 

"Should I get him an instructor if he wants to learn? I thought it be better to wait until he was 5."

"Whatever you decide sir." 

Zeoticus smiled. 

"In that case, come here." 

She smiled as she walked over while unbuttoning her maid outfit.

"Of course."

While Zeoticus was involved with his maid, Romonus had read through a book on controlling Demonic 'Power' or Energy as he called it. Pretty much, what he had been doing was the correct method and there was no secret technique. 

If anything every Devil had their way to make it work and his 'string' method was working. It was not the only one he had as there were several, but it was worth it. He placed the book on the pile and opened up a book on Beasts of the Underworld which were numerous. 

Some were common, rare, extinct, or almost extinct for their unique parts. The same with magic herbs, and magical metals. Every bit of information could be useful, but once he felt he read enough he put the books back before leaving. 

No one bothered him about his reading for a while, but one day his Father called him to his office. Wondering what he did wrong, Romonus walked into the office. 

"Yes." 

Zeoticus smiled as he kneeled. 

"Romonus my boy, come. I wanted to ask you something." 

"Ok." 

He ran over into his Father's arms who picked him up. 

"You sure are growing heavy. Maybe you need to eat a little less." 

"No, I will get hungry." 

"Alright, your food stays the same. Now, I wanted to ask about your reading. Do you like learning?" 

He nodded with a smile. 

"Uh hu. Fun." 

"Well, would you like me to get you an instructor? They will teach you all the things you want to know." 

He instantly pictured someone like Gandalf, Dumbledore, or Merlin so he nodded. 

"Cool magic? Boom." 

He exaggerated his actions making Zeoticus laugh. 

"That too of course. I should be able to get a good one, just give me a week or two." 

"Ok." 

He hugged his Father before he ran out of the office. That made Zeoticus smile as he was sure to get his child a good tutor. One to both teach him in magic and power. He could get the regulars or a new one. He would figure it out in time. 

As for Romonus, he did not return to the library and instead returned to his room. Rias was out with their mother which would give him time to continue his training. He felt that very soon he would be able to begin to experiment with his abilities. 

He could not rush it as they were destructive, Gravity Magic and Destruction both could turn lethal in the wrong hands. While he would be fine to experiment with both it would destroy everything in his surroundings. 

Until he could throw black holes at people, or draw down meteors from space he would not be satisfied.