After Sirzechs essentially told him to seduce his friend, Romonus was in no way opposed. Serafall was a fan favorite of his because not only was she a goofball, she had the power to back it up. He had three criteria for the ladies that would form his harem one day.
Of course, beauty was the 1st, second was drive to improve, third of all was fun, and the chaotic 4th option was to cause as much of a shit storm to Fate as possible. Serafall was single in the series and was only friendly to Issei.
As for the Fate of Issei himself, Romonus could simply murder him to take the Boosted Gear or handle him some other way. Issei was the main character of DxD so killing would not be easy. Plot Armor would activate or something of that nature.
Instead, he planned to allow Raynare to nearly kill him and then come in at the final moment to deal the final blow. It was easily achievable as he could already end a large city at maximum power.
Of course, Kuoh was important, but he would not spend his time in the town. He was brought out of his thoughts when Latia spoke to him.
"I wanted to ask you this, but I saw you talking with Diodora earlier. What did you say to him?"
"Since he is the heir of the Astaroth family, I felt it prudent to get along with him since he is related to Ajuka my brother's best friend. I suggested that we bring our clans closer. Turns out, it was unneeded as that is why we are being engaged."
Latia understood as that was a perfect reason to talk to him.
"Were you uninformed of this decision?"
"I was uninformed. I had assumed my Father would engage Rias, but not me. Turns out he decided to go ahead with it and it seems that we both won out in the end."
Latia hugged his arm a bit tighter as since she was a child she had been told it was her duty to marry a fellow Noble. Her Uncle had told her that the best way for her to take ownership of her fate was to grow strong enough to be able to accept or deny it.
In her case, Romonus just happened to be what she was looking for.
"We should speak to my uncle before he goes off into his lab. We won't be wed until we are both 18 which leaves us 7 years to nurture a relationship. Sad it will have to be long distance."
"Does it have to be? I can visit you as often as you desire and vice versa."
"I would like that, but we both are going to be busy in our time. Puberty is when we Devils undergo the most growth so my time will be spent in training. My Uncle even has thought of passing along his method to me."
Romonus understood her.
"I get it. I will also begin to train not just under my brother's peerage, but under him as well. Now, let's talk to them. I want to get a reaction out of Beelzebub."
As they both began to walk toward the Satans, Latia turned to him.
"That will be hard. He rarely if ever smiles and keeps to himself. Only because I am the daughter of his brother did he ever give me that much attention."
"I have heard that about him. A shame that one of the Super Devils of our race has no interest in the opposite gender."
"Very true."
When they finally reached the Satans the 4 of them turned toward them. Sirzechs placed a hand on Romonus' shoulder.
"Congratulations Romonus. I feel happy for you."
Romonus genuinely smiled this time.
"Thank you, brother. You all should have informed me beforehand. Anyway I wanted to talk to my Uncle-In-Law. Can I call you uncle?"
Ajuka nodded.
"Call me whatever you want. I wanted to inform you that you will be receiving your Evil Pieces in a month. After that, you will be free to begin to explore the human world all you want."
Romonus had several locations in the world where he could find good candidates for his peerage.
"Thank you. I was getting couped up being in the Underworld because of the politics. It might be fun."
Serafall began to laugh after hearing his words.
"In that case are you sure you want to become the next Lucifer? It's full of paperwork and borring meetings."
"Can't I just use a computer to do all that for me? Don't tell me you actually do paperwork by hand."
Instantly, Serafall and Sirzechs looked at each other. They had not thought about it before which made Falbium shake his head.
"Why do you think I have so much time to sleep? My computer does most of my work for me."
Ajuka shrugged.
"Same."
Seeing how he had just dropped a bomb on his brother and Serafall, Romonus sighed.
"Honestly brother, I thought you would know that."
Sirzechs waved him off.
"I am almost 600 years old, lay off already."
Serafall pointed at herself.
"Do I look like someone good with technology?"
Romonus looked down to look at her as she was short. He started to hold back a laugh as she was only 5'2. He was 11 and was already taller than she was. When she noticed she frowned.
"You are making fun of me, aren't you?"
"No, no, no, not at all."
"I don't believe you."
Latia began to chuckle as her uncle and his friends were just a bunch of goofballs with enough power to rule their society. They were just good people who had no interest in world domination or something as dumb.
Ajuka turned to Romonus with a smile.
"Make my niece happy."
Romonus decided to try to play his family card here.
"Then can you teach me the Kankara Formula?"
Ajuka did not straight up say no as he expected.
"How good are you at math?"
Romonus in his past life was a straight-A student, but Math was such a hard subject.
"Above average."
Ajuka pondered on it.
"I will be teaching Latia here so if you come along I can test to see how compatible you are with it. Consider it a gift for joining our families as one."
"Thank you. I will not forget to return the favor."
Ajuka smiled and ruffled his hair.
"Just keep being the same and don't go wanting world domination."
Romonus had no interest in that.
"Ruilling the world is dumb. I much rather spend the time on my hobby."
Just as Ajuka was going to ask what it was, Zeoticus spoke once more.
"Now that my children have had the chance to speak to their future spouses, I think it is time to wrap up this celebration with a dance."
Romonus turned to Latia as it was a good chance to show off his dance skills. He had been taught dancing by his Mother and he had taken a fancy to it thanks aiding his footwork.
"Would you honor me with a dance?"
"Of course."
They were not the only young couple as many Nobles had been engaged much younger than them and already either close to their finances or growing closer to them.
Some Adults decided to dance like Lord Sitri and his wife Lady Sitri, but Lord Bael did not. His uncle was a cold and reserved man so his wife instead stood by his side in silence. Regardless, he ignored all other distractions and instead focused on Latia.
"Are you familiar with Tango?"
"Of course."
Romonus wrapped a hand around her waist while she placed her hands in his. From there, they both got rid of all distractions and began the dance of Tango. This was the first time they had met and a dance like this was a very intimate moment.
The both of them started slow, but quickly they began to find their rhythm. Latia and Romonus quickly started to become the center of the room as their dance began to pick up pace.
Latia's mother openly wept at her daughter's dance while her Father looked over to Ajuka with a smile. Ajuka looked back at his brother and smiled back. They had done the right thing and found the perfect partners for Latia and Romonus.
Just as no one expected their dance to become even better, their pace seemingly doubled. They began to move through the dance floor in a flurry of footsteps and dance moves.
Rias who was still with her mother covered her mouth as she got a little teary-eyed.
"So beautiful."
Venelana smiled as he hugged her daughter tight. Just then Zeoticus walked up to her and extended his hand.
"Love of my life, dance with me."
"Zeoticus, it's been so long."
"I still remember the way you dazzled when we met."
Rias pushed her mother to go with her Father as this was why she wanted to find who she loved. Venelana had told her how her Father stole her heart and she wanted to see it. With that push, Venelana took her husband's hand and joined him on the dance floor once again.
Sirzechs then turned to Grayfia who was still holding Millicas.
"Grayfia my dear."
She smiled as she handed Millicas to Serafall.
"Hold him."
"Uhhh, sure."
Once they were dancing, three pairs of Gremory were locked in their dances. Rias was sad she had no one, but she would rather die than dance with Riser. She looked as Latia lept into the air and Romonus carried her with grace.
They continued their lightning pace, but to Devils like them, it was a regular place. When the dance finally ended they both looked each other in the eyes. That simple gesture meant too much to them.
When every dance ended Zeoticus turned to address the guests.
"Thank you for coming everyone. Let's all wish the new matchings prosperity."
Following his statement, a cacophony of applause filled the ballroom. Romonus and Latia gently rested their head against each other as they enjoyed the other's company. This was the first time they had met and it had gone great.
The celebration ended up lasting a few more hours and ended when all of the food and drink were done. Once the guests began to leave, Romonus and Latia exchanged contact information as phones were a thing in the Underworld.
Riser tried to do the same, but Rias shot him down and refused to even talk to him. That angered the Phenex heir, but his brother Ruvel pulled him along with the rest of the family. But, once the mansion was truly empty, Romonus walked toward Rias.
"Tomorrow at 7 AM. Wake up on time ok?"
Rias nodded.
"I won't slack off anymore. Count on it."
"I do."
With that goodbye, Romonus returned to his room and opened it with his key. Once he was inside, he brought out the hair of Diodora. As he looked at the blue hair of one of the shitties characters he thought about it,
" I better call my teacher, he will hear me out."
MacGregor Mathers was not a noble individual and was open to anything in exchange for magical research. He had learned many Black Magic spells from his teacher and this was one was one of his creations.
He called it the Call of the Harvestor and if it worked, the heart of Diodora would be in his hands. Of course, if it went wrong he could end up with his heart out of his chest so caution was advised. That was why he had to be cautions as rushing into rituals was dangerous.
For now, he pulled out his phone and called up his teacher. The phone did not ring for long before it was picked up.
"Romonus. What do you need?"
"Master, I wanted your aid in a less than noble experiment."
"Explain."
"Of course. I made a spell of my own as I want to use the Ritual of Purification. I have picked out a Heart, but it's owner still has it."
"Who is it?"
"Diodora Astaroth."
"For?"
"It's a long story."
"I have time."
He sighed.
"Fine. What do you know about the future?"
"Not as much as I should. Can you see the future?"
"Maybe."
"Stay in your room. I will be there and you better convince me of this yourself. Got it?"
"Yes."
Romonus backed away as the teleport circle of his Magic teacher opened up. From it emerged MacGregor Mathers the best Bishop of the Underworld.
"Explain to me what you know?"
"Alright then. Buckle up."