To remind for people that this an AU universe of DxD. Meaning, that certain people didn't marry, certain ships sunk in world war 2, certain swords were found early... and certain other thinks which I don't want to spoil. Now of to the Smut since this is DxD...
~~~~~~R-18 stuff, skip to 'next morning' if you don't want to read this~~~~~~
"Shall we 'practise' kissing first?" Serafall asked with a lewd smile.
"Indeed we need to run some tests on that one," Marcus responded while holding the sexy devil lady's assets with both of his hands.
Hearing his response, Serafall immediately remembered role-playing, more specifically, science-type role-playing…
She needed to get her hands on some sexy glasses and a lab coat, for the future…
"Shall we commence then?" The sexy black haired devil requested with a voice that reminded Marcus of those serious science-ladies he used to work with in his previous life.
"Test number one…" Marcus stated as he leaned forward and claimed Serafall's lips, the moment their lips touched, the beauty instantly pushed forward and started a make-out session.
Just a few moments later and her eyes were already glassy.
Soon enough, her hands started to wander around, as she started to undress him. Her Master quickly joined in and removed her skimpy shorts and t-shirt.
Their kissing had to abruptly stop as their clothes were simply in the way.
When Marcus saw Serafall's underwear his eyes were slightly widened, they were extremely sexy! She was dressed in a black, almost see-through lingerie.
"Like what you see? And you know the best part? I can dress however you want!" She gave a seductive wink.
"I will...keep that in mind, for future reference…" He answered with a gulp. Because they were almost naked, he could practically feel her warm body against his.
"You better! I can't wait to see how you will dress me up!" She said with an excited smile before focusing back on the matter at hand!
"This here~~~ is for me, isn't it?" Serafall licked her lips, before pulling the last pieces of clothing off her Master's body.
When she saw that he was already rock hard, a purr escaped from her lips.
"How do you want me, Master? Shall I serve you now? Or do you just want me, like this~?" She asked hotly as her hand went onto his rod.
'And he's still growing… this is going to be so good!' As she stroked her Master's cock, the devil lady licked her lips in anticipation. She was already enjoying this and it was only gonna get bigger in the future
"Show me how good Satan Leviathan is at serving her Master." Marcus demanded while stroking her cheek.
"Fufufu… as you wish…" The beauty elegantly moved on to her knees and started serving him.
Marcus groaned in pleasure as she put her hot lips around his shaft, and it was only the beginning as she quickly escalated to the next level and started using her breasts. The bra was long gone as she continued to undress. While sucking on his rod.
The devil beauty very quickly started moving up and down on his shaft in a rapid tempo. It almost felt like she was starving and his cock was the only food source available to her.
With a groan, Marcus came hard in her mouth and Serafall very greedily drank it all.
The inventor was quite shocked at how shortly he lasted but then again his new body has no experience with females at all!
Serafall drank it all masterfully before pulling back, she looked with glee at how quickly her Master was recovering from his first release.
She stroked the shaft once more, watching as it slowly went full mast for her. Once it was ready she got up onto her feet and started removing her panties slowly.
Making sure Marcus saw every last detail of it.
"How do you wish to proceed with this test?~~~" She asked seductively with one hand on her hip.
But instead of receiving an answer her Master simply grabbed her and pulled her onto his lap.
The black-haired devil lady purred once more before wrapping her arms around his neck. She positioned herself right on top of his rod.
Moving back and forth, teasing it with her pussy lips. Marcus, who simply had enough, grabbed her ass and unceremoniously pushed her down on his rod.
"Hhmmm~~~ that's it…" Serafall moaned as she felt invasion in her cave. Her pussy was sucking on him hard. She has been waiting on this for months… she can't remember the last time she was this horny!
The simple insertion was almost enough to make her come hard!
Before long, his rod was fully inside. The beauty could not control herself anymore and started moving her hips.
At first, her movements were a bit slow but as she kept moving her waist the speed quickly increased.
"Mmhhh~~~"
"Hnnn~~~"
"Leave this to Sera, Master~~~ this test is all mine~~~" She said while changing position slightly leaning back, showing him her impressive rack.
Marcus' hands moved onto her very enticing breasts, he needed to 'test' their elasticity after all.
Serafall grinned silly seeing her Master's expression, it was of a man trying very hard. She was riding on his cock and he was trying hard not to come while thinking of touching her even more.
Nonetheless, Marcus didn't last long against Serafall who was as hungry as a beast. And before long ropes of cum were shot into the Devil Lady's womb.
"Hmmnnnn~~~ it's here… very good~~~ a very successful test~~~" Serafall commented with glassy eyes.
"...A very successful second test… we shall move to the third…" Marcus stated as he grabbed her hips. Serafall eyes slightly widened in surprise before she had a very lewd smile on her face.
"Ohh~~~ Master sure has great vitality~~~" She said with a purr… Serafall felt him channelling magic throughout his body as she wondered if Solomon had left some magic techniques for intercourse… After all, the man had a massive harem!
Before long, Serafall was flipped over and laid on her back, both of her legs were high up in the air.
She was liking this even more as her Master took control and was taking charge.
Seconds later and she was already softly moaning from his movement.
The beauty wondered how long he could last? Especially since this was his 'first time'!
~~~~~~Next Morning~~~~~~
When Marcus opened his eyes, the first thing he saw was his room's ceiling. Everything was normal, just like he liked…
Or it should be. But instead, he felt a heat source next to him. Instead of reacting to it he took a deep breath and smelled the familiar scent of his devil girl.
He understood that Serafall decided to sleep with him. Instead of reacting to that in some weird way he just wrapped his hand around her and decided to continue sleeping since he still had around an hour until he needed to wake up.
'Hmm sleeping with Sera is quite nice. I think I can get used to this everyday.' With that thought in mind, the young inventor immediately snoozed off.
And Serafall, who was sleeping on his side, smiled a happy smile. She wanted to figure out what his reaction to her would be. And to her satisfaction, it was a very positive one.
Since he likes cuddling, she decided to wrap her arms back around him as well. The black-haired devil lady decided to stay like this for a few more minutes before she would need to move.
~~~
At 7 o'clock in the morning, in a certain room an alarm clock rang. Marcus opened his eyes and got out of bed, he rushed into the shower first thing in the morning, to get rid of his grogginess.
After he was properly woken up by the shower, he went to dress up in his school uniform. That moment he realised that his heat source was gone. He turned around and scanned his room with his gaze.
His room was kept as simple as possible, as he prefers to customise his workshop over this room.
After looking around he realised that Sera was not in his bed. Meaning that she left before he had woken up.
'I didn't even feel anything when she moved, she is either really sneaky or I am just that deep of a sleeper?' He mused to himself. Since she is registered in the system as his familiar, his barriers didn't even bother to pick her up.
Once he was fully dressed up, he fixed his bed and descended to the kitchen…
The moment he arrived in the kitchen his brain stopped for a second.
He saw Serafall talking to his mother and father very animatedly. She had her hair done into a high ponytail and was wearing 'smart' glasses. She was also dressed in his school uniform making her look no older than a smart-looking sixteen-year-old girl!
That's the thing about the current Leviathan, she can easily pass as an early adult or a late teen…
"Mark! You never told us you were 'friends' with an older girl!" Marcus' dad said with a grin as he purposefully emphasised the word 'friends' .
The reincarnated inventor simply rolled his eyes. He was trying to spend less time with his family on purpose. So that, to anyone else -mainly the devils- it would seem like he doesn't care much about them.
The less attachment his enemies knew he had, the more leverage he had over them. But it would seem that the moment he gave some space to Sera she took it to the next level.
Fortunately, he knew that she has a large amount of affection towards him, and his Ars Goetia was telling him that she was only curious and wanted to learn about his parents. And not use them. That was the only reason he was allowing her to act like a '16-year-old cute girl' who is interested in the loner Marcus…
"Yes, we are for quite some time now. She only decided to come here now because it was convenient." The teen inventor said with a sigh as he took his seat. Amusingly enough it was right next to Serafall. Seeing the coincidence, both his parents were grinning like idiots.
"Indeed, I have known him for over a year now. And yet, I still find new things about him each day." The black-haired disguised devil said with a smart-sounding tone. Her acting was utterly and insanely on spot. Even Marcus could feel a chill going down his spine at how good she was with it. It was no wonder that she is responsible for diplomatic relationships...
"I see… Honestly, Son, I thought you were going to marry your BMW at this rate" His father said sagely. He was expecting Marcus to marry his car.
The teen inventor rolled his eyes as he started drinking his tea.
His mother coughed in amusement while Serafall simply just smiled.
"Don't worry. I will make sure he doesn't do that." The current Leviathan said in an assuring tone.
"We leave him in your hands then, Sera." His dad said with a serious nod.
This made the teen groan. Why do they have to take these small inconsequential things so seriously?
~~~
"Is there any reason as to why you suddenly decided to insert yourself into my morning rituals?" I asked with an eye roll.
Nonetheless, I do love how she is hugging my arm and acting like a doting girlfriend.
"And why not? I have already altered some of the hypnosis done by Venelana. They are much happier knowing that their son has a girlfriend!" Serafall said to me while continuing to hug my hand.
We were reaching the school and I can already see some people staring at the black-haired devil girl of mine.
Her beauty is supernatural, and to be perfectly honest, I began to completely dismiss the 'regular' girls.
It was like they were 'colourless' and didn't have that 'colour' Sera has. I mean, I could still get turned on by 'regular' girls but actually being interested in them? No, not anymore.
"As long as I have my time and they are not snooping around the area behind the garage it's fine," I said with a sigh. I suppose I could accept the fact that Serafall is advertising herself as my girlfriend.
"Don't worry, I dealt with that the moment I started the hypnosis. They think that area has some miscellaneous stuff laying around. They won't be checking it unless some sort of cleaning is done." She explained to me.
"I see. I suppose I could make it look like that." I said with a nod, thinking of dealing with it.
"Indeed. Now why don't we act like an actual couple for once!" She proposed with a suggesting purr.
"As long as you don't overstep your boundaries, Sera. I will entertain this idea." I agreed with a nod.
She smiled hearing that.
"Don't worry~~~ you forget that, I am a devil~~~ I can adapt to any situation. I know my boundaries. I won't be interfering or demanding too much attention. But, I will be there when you are free… or more precisely, you should call me when you have the time… I can always help you~~~ in some way~~~" She winked seductively before entering the school.
I can assume she already inserted herself in the educational system of my birth country.
Hopefully Heaven or Norse won't notice her profile picture… Well, I don't think they even have profile pictures here yet.
~~~
"Marcus!!! Let's have lunch together!" Serafall entered my classroom with a lunchbox in hand.
I lifted my head from my notebook and saw her smiling at me. The people who were in class were looking at me as if they had just seen me for the first time in their life.
For obvious reasons, I am much more reclusive in this life than I was in the first one.
And my school attendance is nothing more than to keep the charade of a regular life going on.
Plus it helps me think about stuff and actually be away from my workshop.
"Dude! You have a girlfriend!? But you never even leave your desk or talk to anyone!?"
"Yeah! Like how!?"
Some of the guys started talking and even had a jealous look after seeing Sera. The devil girl's supernatural aura and looks just suck everyone in.
"Marcus is like, super smart and top of the school lists~~~ did you know that he is also super good with his hands? Like really good?" Her words made girls blush as they were thinking of it as a sexual innuendo…
"He is also fixing a completely broken car from top to bottom in his free time! He is super cool and hot!" Serafall acted the part of a doting girlfriend, making more people jealous…
I decided that it was time to leave the room. So, I quickly collected my stuff and left the classroom. I could practically feel the amount of eyes on me, especially when the black-haired devil hugged my arms tightly.
~~~
"Let's find out what your tastes are, Master~~~" Serafall said as she opened the lunchbox. There were a ton of sandwiches there.
Just from a glance, I could tell that each of them are different in their own way.
"I have prepared multiple sandwiches with different ranges of tastes. This way I will find out what you like and from there I will work my way up to make even more things you like." She said happily as she offered the sandwiches to me.
"Or… you could have just asked what I like…" I said while picking up a random sandwich.
"Where is the fun in that? Besides this way you might also find a liking to a new taste yourself." She said while waiting for me to taste it.
"True… let's see then…"
I took a bite, and the first thing I noticed was that my mouth was suddenly assaulted by the spiciness which was then washed over by the sauce the next moment…
"This… is… good… I dislike spicy stuff but this is good! Especially this! It allows me to taste spicy stuff without burning my mouth. Very good! 10/10!" I praised her, the smile she gave me reminded me of a cute animal, if she had a tail it would be wagging right about now.
"I know right! Anyway! Try this one!" She quickly pulled out another sandwich after I finished the first one.
'Well, this might be a good thing, My school time is quite dull after all.'
For a second I thought about how different this was from my previous life. Back then I only had a few people of which I used to talk to cars about, since nobody watched anime or played video games during that time…
Well, they do, but no one talks about them in school. It was too embarrassing in front of the girls, so we ended up only discussing cars.
But, ever since I ended up in this body I didn't bother making any sort of friends since I had little time for it.
Now with magic, it's even less possible since... Well, magic and the supernatural. Regular people don't have a place in any of this and because I got myself involved with the devils I would rather not get close to any of them.
That, however, came to a question with Serafall coming into my life.
"What do you think? Are they good?" The devil lady brought me out of my reverie, I turned towards her.
"This is good. All of them are nice, some better than others, I can assume you will be making them every day?" I asked with raised eyebrows, since she is spoiling me like this, I won't be holding back.
"It all depends on you, remember? You did say that I belong to you, no~~~?" She asked with a coy look.
"Indeed. Then I request this daily, since you started this trend yourself."
"I had to, you were turning into a machine. It was up to Sera to fix it!"
"I see… I suppose I was turning into that. But that was so that the basics could be done." I said with a sigh.
"Basics? You mean inventing futuristic technology and making a pantheon-level protection barrier were only the basics?" She asked while shaking her head.
"Indeed. One needs to fortify his base before expanding outside." I sagely said with a nod while thinking about precautions in case Serafall's actions would raise any suspicion.
Actually, it has already raised some suspicions. I heard Sirzechs was already looking into her.
"Sera, you mentioned spies yesterday? Has anyone been snooping around you lately?" I asked quite seriously and Serafall stopped in her tracks.
"Nothing of concern. Sirzechs only sent some people to find out about my increased speed in paperwork. Naturally, he could not find anything as there was nothing of note in my office.
So far, nothing that is going requires us to act. But… knowing him… he isn't going to stop until he finds something…
In conclusion, we need to prepare something, otherwise he might just push me to the point where I need to have an answer of some sort prepared for him.
Worst case he will send Grayfia after me to spy on." Serafall gave me an answer. And this was exactly the answer I was expecting. Sirzechs will do something.
'Grayfia is an issue, she is a devil from an extra house. My Ars Goetia does not affect her. That means I need to come up with another binding method. Another concept to base the binding.'
'She is a servant of Lucifer if my memory is right, Venelana barely covered the extra houses since there are so few of them left.'
"I see if that's the case I need to think of countermeasures, in case you need to talk," I said to her after thinking for a while.
"...Master...I hope you are not thinking of making me fight them? I might be strong but Sirzechs is on a completely different level…"
"No such thing. There is no need for you to fight anything. Ars Goetia will pull you to my side in case you fall under some sort of suspicion. The course of action for you is to reveal that you have a contract with a genius inventor. This will cause some publicity for me, but it's better than you losing your position.
If it comes to that, we can think of future actions once we reach that point. For now, we need to think about countermeasures in case my location is discovered." I said while continuing to think.
Serafall released a sigh of relief before thinking for a moment.
"Doesn't the Diamond Heart Core make it nearly impossible to pinpoint the coordinates of teleportation?" She asked me with a thoughtful look.
"Not quite… they would know the general direction. For example, if you were to jump from America to here. People would be able to track the general direction of it. Meaning Europe, somewhere towards Asia. This means they would be able to pinpoint that it's Eastern Europe.
It's even more accurate if you teleport from the Underworld. If anyone were to track the teleportation they would know that you ended up in Eastern Europe. But that would raise some suspicion as your direct location can't be tracked."
"...This means they will be suspicious because I am hiding something…"
"Correct. That's why you need an alibi…"
~~~~~~Underworld (some time ago)~~~~~~
A certain red-haired man was sitting in his office, he was radiating an extremely serious aura.
"Grayfia...I need you to find out how Serafall is doing her paperwork. It's of utmost importance that you find out." The current Lucifer said with a deadly serious tone.
"Can't you just ask her how she is doing it?" His Queen asked with a confused look. She was baffled that he asked her to spy on a fellow Satan!
"Already did… she dodged the question multiple times. I realised that she didn't want to share it" The red-haired man explained to her.
"Then… there should be a reason as to why she doesn't want to share it." Grayfia reasoned with him.
"Indeed. But, I need the truth. She finishes all her work before midday. Such a thing is unheard of. If I could do such a thing then I would have much more time for other things than just paperwork!" He said the last part with a chilly icy tone. His eyes slightly glowed red as he looked at the mountain of papers at the edge of his desk.
He was about to use Power of Destruction on it but changed his mind at the very last second.
"Very well. If this is what you wish. I will do this for you."
"My thanks, Grayfia." The current Lucifer nodded before returning to his work.
While his Queen left after bowing to him.
~~~~~~Few Weeks Later~~~~~~
The Strongest Queen has been trying to figure out what was going on with Satan Leviathan.
At first, it was just her mission entrusted by her King. But then she realised something was going on with one of the strongest members of their race.
Serafall was much happier… Not that fake Magic girl act. In truth, she has not seen Leviathan wearing a magical girl outfit for some time now.
This points towards something that is going on with the fellow devil. Grayfia concluded that the black-haired Satan was most likely dating someone.
The happiness, the changed behaviour, she has seen this kind of thing before. But, this still does not answer the question: how is Serafall doing her paperwork this fast?
While the silver-haired maid didn't like the fact that she had to continue with her spying, she still tried but. In the end, she couldn't find anything.
This only leaves her with the fact that she needed to track her down in the human world…
Easier said than done, as Serafall really doesn't want to be discovered. Secrecy to this kind of level for some reason disturbs the Silver-haired maid.
She can get the fact that Leviathan is a public figure and she wants her own private life, but this amount of secrecy even towards the teleportation circles is over the top. No one in the Underworld hides their teleportation destination to this level.
'Eastern Europe… that's dangerous Serafall, why are you going to Church controlled territory?' Grayfia tried to pinpoint the teleportation with her magic but she found out that she had immediately lost the black-haired Satan in Eastern Europe.
Nonetheless, she now knows the general location, although this might take several weeks, maybe even months, of careful searching…
~~~~~~Marcus~~~~~~
It was finally time to test the holographic design table. After finishing the basic OS, the table was now functioning to a usable level.
The whole PC and table designs were done months ago. But the OS took ages to program. Even with my augmented talent, it still took months since I was working on making it a self-updating one for the sake of saving time.
There are shackles in places. I don't want a rogue A.I capable of designing tech and magic weaponry running in the supernatural world after all.
So it has certain restrictions on how it can self-update. Nonetheless, it will eventually be a virtual butler capable of helping me in the field.
After thinking about it for a bit I decided to upgrade M.T.M Castor MK II to the next level.
For that, I scanned the paper design and uploaded it to my PC. Going through several filters I could now see the 3D image of the gun.
At the current level, to interact with the holograms, I still needed to wear specific gloves. These gloves will help collect all the data on my movement and cross-reference it with the hologram. This will help to improve the hologram and the interaction from humans to the hologram.
Eventually in the next level, I won't need to wear gloves to interact with the hologram.
But to reach that level, I needed to use the table in the first place. That's why I am already using it although it was quite uncomfortable.
First I stripped the gun of its case and left only the M.T.M circle technique.
Then I upgraded the M.T.M onto the next level, with more accelerator circles, magnifying circles, as well as booster ones. This made the system much bigger but that's the point.
The gun will be bigger, if the gun is bigger then, the rail can also be longer. The longer the rail is, the more power it can create.
Speaking of the rail. Next is the Barrier Rail Technique, or in this case Barrier Rail System.
For this one I decided to make diamond rails powered by magic. Not only will it accelerate even further, it will generate heat and friction both of which will be absorbed by the barriers around and then added to the load at the very end.
This whole thing would increase the power of the shot from around 300% to 400%. In other words, even a regular man could technically kill a high-class Devil with this. Just by pressing the trigger.
While all of this was nothing more than upgrading already existing techniques or in this case systems, I'd started working on the cartridge system.
The basics were quite easy. Scatter fire, or beam version. Or even cannon fire. Those are simple magic manipulations. Done through a circle.
That's why it was time for me to summon my first devil familiar…
"Well, I am almost done with the internal design…"I said to Serafall who was doing her paperwork.
"Hmm? That was quick… I thought you were going to spend days on it." The current Leviathan said with a curious look as she just pressed YES to sign a paper.
"As if… I am not doing this on paper anymore. And I'd already reworked the two main points of it, and now I am working on the cartridge. For that, I will need to summon Venelana." My words stopped Serafall In her tracks.
"What...for?"
"Her Power of Destruction," I said plainly. And Sera sighed in relief after hearing that. Is she jealous or something? Does she think that I will have my way with that brown-haired devil lady?
"I see… are you planning to recreate it?" She asked me after fully realising what I just said.
"Indeed. More like synthesising." I said to her, Before focusing on my Ars Goetia and connecting to Venelana.
'Venelana it's me. I will be summoning you soon, get ready.'
'O-Of course…' I got a shocked response from her. Well, I would be shocked too, after not talking for more than a few years.
A few moments later Solomon's circle appeared and Venelana appeared in all of her physics-defying glory.
The first thing she did was obviously to look around. Her eyes eventually ended up on Satan Leviathan…
"L-L-Lady Leviathan!? Y-You are here!? D-Does this means…"
"I am his Sitri Pillar." Serafall casually nodded at Venelana.
"No...wonder… no...wonder I was not summoned anymore…" the brown-haired devil lady was looking at the tiled floor. Her shock was obvious on her face.
"Not that you need to be summoned… you can summon yourself. I do that every day. I am the one who keeps him company in any way he wants…" Serafall words had many meanings and it would seem Venelana understood that very well.
"Anyway. Let's keep this short. I only need some of your power of destruction. Once I scan it you can return to the Underworld." I got her attention back with my words.
She turned around and looked at me from top to bottom. A bunch of emotions went through her eyes at that moment.
"It's fine. I have more than enough free time these days and I haven't seen you, Master, for more than two years." She said with a certain tone.
If she doesn't want to leave then, there is a hidden motive. Well, we will have to see what it is that she wants. It would be quite interesting to find out…
'I should have asked Serafall about the political landscape of the devil.' For a second I thought about it. But decided to drop it for the time being.
"I see… then you can stay if you want. Let's get the Power of Destruction reading done first." I motioned for her to come over, where a white circle was getting prepared.
"I need you to create a ball of Power of Destruction and make it float inside that circle for a certain amount of time. Can you do it?" I asked her while walking over to my computer.
I could see that the circle was properly connected to my PC.
"Easy enough. I can assume you are trying to recreate it? While I have no doubt that you could do it. You do know the repercussions of doing so?" Venelana asked me with a sigh.
Satan responsible for diplomatic relationships in my garage. I know more than I need." I said with an eye roll.
"If you say so…"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Along with the advanced chapters, there are also a lot of other fanfics I wrote and did not upload to Webnovel.
P.S: To clarify, chapters are coming out Monday, Wednesday and Friday around 9:00 AM British time.