The Knight of Ruin(DxD)

Souji was never physically mighty as Romonus could outperform him in strength many times over. He never specialized in strength or put the most power behind his sword. Instead, he had focused on being the fastest.

As a human, his sword style favored quick-paced moves and control which became his signature skill as a Knight, godspeed. He was both the fastest and most skilled Knight of all Devils. He had done his best through the years to improve and he had grown a mastery of his Knight pieces no other had before. 

Ever since he began to train Romonus in the art of the sword, he saw how Romonus took his teachings and changed them to suit his style. Thanks to Surtr's insane training he had unlocked Touki a rare skill among Devils, and MacGregor taught him to use his sword as a magic focus.

Now, he was going to show him that one didn't need to be skilled in magic or physically powerful to win a sword match. Romonus gripped the handle of Blood Drinker with both hands as he pointed it toward Souji. 

Souji held his Katana with both hands as both of them stood still. Time began to slow down as both of them let go of everything and focused on their swords. Rias clenched her hands together as she waited for the moment they moved. 

When she blinked they had already vanished reminding her that her brother had many years more training than she did. Romonus had taken the teaching of Souji and his godspeed training for himself. 

Of course, he was not yet as fast as his teacher, but he was getting there thanks to his much stronger body. A thin layer of Touki shimmered around his body while the Demonic Energy inside his body increased his physical ability. 

Both abilities together allowed him to blitz forward as he swung his sword down toward his Master. Souji though released a hand from his sword and swung upwards against Blood Drinker. Using pure skill he raised his hand and made Romonus swing against the ground. 

'Don't think so.' 

Romonus gripped the handle of his blade, spread his feet out, and swung back up mid-swing. Vespera as the core of the Demon Sword channeled her own Demonic Energy which was massive into the swing which Souji felt. 

The Knight kicked off the ground and lept out of the way as an energy wave of Demonic Energy and Touki cut through where he was standing. He grinned as he formed a platform of Demonic Energy and kicked off it to jump down. 

"We're picking up the pase. Speed trumps power." 

Souji vanished as he swung his blade toward Romonus' neck who reacted on pure instinct. Touki allowed one to react to threats against their life so he swung Blood Drinker down and clashed against Souji's Katana. 

Souji was stopped in his tracks thanks to Romonus' raw power, but he knew Souji was holding back. In the Light Novel at full power, Souji cleaved a leg off the Jabberwocky a 200-meter-tall monster created by Annihilation Maker with ease. If he had wanted to, he could have taken his neck at that moment. 

He still took it as an achievement that he caught the swing. Souji himself was impressed as he moved faster than he usually did in their training matches. 

"You managed to catch my blade. Impressive." 

Romonus smiled and sighed. 

"If you wanted you could have cut through Blood Drinker and my head in one go." 

Souji pulled his sword back.

"Of course, but I have had over a century to perfect my sword skills. You have not and still you caught my blade. Not just anyone can do that and besides you are not a swordman. You're a Spellsword, you fight best with your Power of Destruction, Gravity, and Spells. If we went all out you would do much better." 

Romonus smiled as he did have the best teachers. 

"Alright, then Romonus, now time to help you improve." 

Following the testing spar, Souji spent another hour and a half instructing him on the art of the sword and the technique of godspeed. Romonus' use of it was weaker because while he was insanely fast he never specialized in speed. 

Souji wanted him to rectify that in self-training as he was just an instructor. It was up to Romonus to change it for his use. As for Rias, Souji gave her minimal instruction and left that up for Romonus. 

Souji turned to Rias and patted her head with a smile. 

"You know, instead of having you just throw Power of Destruction at me, throw it at your brother. He is immune to its effects and he is an actual user."

Rias smiled and nodded. 

"Yes, Uncle Souji." 

Souji smiled in Romonus' direction who merely waved him off. Souji vanished after that leaving Romonus and Rias behind. He sighed and turned to Rias who was looking much happier than before. 

"What will you teach me first? The string method, or The End?" 

He snorted. 

"Neither. Those are mine, you have to think of your own use of Power of Destruction." 

"Awww, come on." 

He raised his head high crossed his arms and turned around. 

"Nope. All mine. It took me years to get control over Power of Destruction to form it into thin threads. You don't have that time so find a different skill. Plus, The End needs gravity magic which you don't have." 

Rias looked down disappointed as she thought both those moves were cool. 

"Fine then big meany, what else can I do?" 

He turned around and walked over to her side. 

"Ok, then time to teach you. The first thing is that Power of Destruction does NOT want to listen. Sirzechs has trained for centuries in the art of having perfect control over it while I have trained in shaping it into shape. Watch." 

Romonus released oceans of POD before rapidly turning them into hundreds of threads with ease. He did not use his hands this time and merely used his mind to begin to control them. They spun around him rapidly waiting for his command. 

"Here is the thing Rias, this method came about because of my method to control Demonic Energy. I already knew how to shape my energy into threads, this was just a step in that direction. You won't be able to do this because you have NO control over your Demonic Energy." 

Rias tilted her head. 

"Huh?" 

Romonus waved his hand and dispelled his threads. 

"You just launch waves of Demonic Energy at what you want to attack. Power of Destruction is formed of Demonic Energy, control the former and you control the latter. Get me?" 

Rias now wanted to ask a question she always wondered. 

"Brother, why do you call Demonic Power, Demonic Energy? You're the only one who calls it that."

He sighed. 

"That's what you think about it? I call it that way because it's Energy. Why else? Regardless, to improve in using your POD, you need to get your Demonic 'Power' under your control." 

He said power with air quotes because it was annoying. His way of calling it was better than anyone else. Rias snorted as she began to laugh at him. 

"Ok, how to I control my Demonic 'Energy'." 

She returned the air quotes making him smile.

"I will teach you my old instructors method, the fire method. Make a small fire of Demonic Energy in front of you. No hands to direct it." 

Rias looked in front of her and did as he said doing it rather easily. 

"Ok now make it orbit around you." 

When she added a second one she kept making them spin. 

"Now keep adding more, make them take different orbits, change the colors do what you think needs to be done. Every Devil is different and your path won't be mine." 

She smiled. 

"Thank you." 

He smiled as he dispelled the Bounded Field around them. 

"It's fine. Anyway, I better get moving. I got a date with my fiance today. You know how to teleport home?" 

She rolled her eyes. 

"Duh, I am not a baby." 

He looked up at the sky hearing that. 

"Sometimes I wonder." 

Rias frowned causing her fireballs to burst apart. 

"HEY!"

He just laughed and teleported away leaving her to her self-study. When she got her Demonic Energy under control then he could help her better. Rias sighed before she sat down and got to work on the technique her brother taught her. 

'I will show him, when I make my method it will be better.' 

---

As for Romonus, he teleported to the Astaroth Clan's main mansion. While Latia was not from the main family, she was treated just as important as the main branch because of her uncle Ajuka Beelzebub. 

Now that Diodora was dead, the heir position of the Astaroth clan was open. In the Light Novel, Latia becomes the next heir following the death of the slimy prick. His rotten heart had been put to better use rather than being killed by Shalba. 

It still made him smirk when he felt the sheer purity and power of his energy after that ritual. The use of Diodora had been the right, but now there was no heir. Considering Latia was now engaged to him the Gremory Heir meant two things could happen. 

One where she married him and took his last name or when they wed they ruled both clans with her as the Asraroth Clan Head and him the Gremory head. Two heads marrying each other was unheard of, but he was not one to play by the rules. 

When he arrived at the mansion, he did so in front of the main manor as each one was heavily warded and guarded. If he had tried to teleport in the defenses would have torn him apart or maybe they would not.

He didn't want to risk it so when he arrived he did so in front of several guards. They turned to look at him as he used a Gremory circle. The head guard a giant Devil in full armor spoke up. 

"Are you Romonus Gremory?" 

"Yes, that is me." 

The guard stepped aside and opened the door for him. 

"Enter. The young lady has been expecting you. You, lead him to her workshop." 

He pointed to a random Devil soldier who saluted. 

"Yes sir. Come with me, my lord?" 

Romonus followed the guard who began to walk him through the mansion. While they were walking the guard turned to speak to him. 

"I feel like you should know, the clan is in mourning right now so security is higher than usual." 

He tilted his head acting surprised. 

"Why?"'

The guard kept walking, but he explained. 

"The heir, Diodora is deceased. Assassinated."

Romonys turned full circle to gaze at the guard in faked shock. 

"How? It's been just 2 days since I spoke to him. He was fine then." 

"We don't know. Lord Beelzebub has been here to see what happened and all they found was a pile of ashes belonging to the heir. We have kept it quiet, as this is serious and we have no perpetrator.

Some whisper it was Grim Reapers, others a Death Mage. But the smart know Reapers only obey Hades and he has no love or care for Devils. I even heard stories of a Elder Lich, but the few Liches remaining keep to themselves. Your fiance lady Latia was not close to him, but still. I would not bring it up." 

"Noted and I grieve with your clan. I should see Lord Astaroth and Lady Astaoth to offer my condolences." 

"Please do. The Lady has not left her room since it was discovered, but here we are." 

He led Romonus to two heavy double doors made of enchanted metal. They hummed with many formations that Romonus asked about. 

"Is she trying to keep us out?" 

The guard chuckled. 

"No, keep her explosions in. Be careful, she is always making a new weapon, armor, machine, or whatever else comes to mind." 

Romonus pulled out his phone and first called her. Inside her workshop, Latia was wearing a heavy protective equipment as from her finger nails a bright blue fire welded some metal plates together. 

She had turned the Mech she was working on into a set of Power Armor as she got inspired by some more anime and video games she watched. However, when she phone rang with her special ring tone she smiled and used telekenesis to bring it near her head. 

"Romonus, are you here?" 

"I am outside your workshop." 

She perked up hearing that. 

"Come in then. I have been waiting to show you what I have been working on." 

Outside, Romonus looked over at the guard who smiled at him. 

"Those doors weigh 5 tons each, they are opened with some pistons. Just let me-" 

"No need." 

"Huh?" 

Under the gaze of the shocked guard, Romonus with ease pushed open the doors with just his raw strength. Latia turned when she saw the door opening on their own. Though when she saw it was Romonus she smiled in admiration. 

'I can't wait to see him in this.' 

She hand't had someone to give this suit, but she now found the guy.