I got this idea after watching season 4 finale and thought what if this happened, also there might be a little bit OOC with the characters; so... sorry? I'm trying to get them close to their light novel counterparts.
Underworld, Gremory mansion, West wing, Second Floor Library. The night of the school festival, just after the rating game.
Grayfia was sitting in the exact spot that Rais had, when she and her 'family' had done training ordered by her brother; Grayfia had been sitting there since morning and it was now night as she had used a spell to see what time it was. She had been pouring over one of the many Underworld law and regulations books, looking for a certain law that had came to her mind when her husband, and her king, Sirzechs had mentioned he should give Issei a reward for rescuing his sister during the Loki Inccident; she was about to close the book when she finally found what she was looking for. She quickly grabbed the book and quickly walked to the throne room, there she saw Sirzechs in a red Gremory magic circle, about to leave for the festival. "My Lord, wait." She called out to him getting his attention, he turned to her with a welcoming smile on his face, "Ah, my love, are you going to be 'cuming' with me to Rais's festival" he said as he let out a little chuckle at his own joke; Grayfia just ignored her husband's perverted joke, deciding to get him back later for it. She then remembered the matter at hand, she showed him the page in the law book, pointing at the section she highlighting with her finger, the great lord face turned from confusion to one of understanding with a slight smirk, as got the idea that his wife was trying to show him; "Things are about to get a whole lot interesting" he thought as while looking at the book. He then looked up at Grayfia and said " Grayfia, why don't you be a dear and let Millicus know that we are going to see his aunt." Grayfia did a bow as she replied to his request "As you wish, my lord", she then turned and left with a smile on her face as she went to get her son.
Rais and Issei broke apart, panting as a string of siliva connected the two, they had been making out for past couple minutes, to make up for the interuption from the rest of the occult club; both red from blush and breathlessness. Rais then said "My answer is yes, I do love you Issei and I would happily be your girlfriend", Issei was about to reply when the doors to the main hallway opened; Rais turn in the direction of the intrusion, about scold whoever it was that interuptted their special moment with Issei. Her words dead on her lips as she looked into the eyes of her brother, Issei also had turned his head towards the sound and immediatly broke his loving embrace with Rias; the glare from The Great Devil Lord had made Issei think "If looks could kill, I would already be dead.". "Onii-sama, what are you doing here?" Rais asked her brother, Issei could sense the uneasiness in her voice, "Rais I have come with good news" Sirzechs said with a straight face that turn with into one with a smile "You are to take in another arraigned marriage that will help the in the long scheme of the underworld." he continued; Issei turn to her and saw her horrified face at what was to come. So he stepped in front of her as well as activated his sacred gear and stated "Whoever you picked will have to through me to even get a handshake with Rias", Rais just smiled at what her newfound lover said; she then stepped beside him and took hold of his hand.
She then stated as well " And also tell him if he even tries to kill Issei, I'll send him straight to HELL." she said defiantly. Sirzechs just started laughing at what his sister and her pawn said, "Well that would be hard to do, Issei-san, unless you can fight yourself." he said once his fit of laughter was done; Issei just looked at him confused until a couple of seconds later it dawn on him. He then looked over to his now fiancee, her deep red blush confirmed what he had heard; he then looked back over to Sirzechs, who had a book open to a certain page, showing them an article on the page. Rais and Issei took the book and headed to her desk, they were shoulder to shoulder looking over an old leather bound book; "Take a look at paragraph 5, subsection C." the devil lord said with a smirk. They looked at the part and saw that it was called Titles and Heirs Regulations for Recently Promoted Devil, they then looked up at Sirzechs, who indicated that he wanted it to be read out loud; they then read out loud together:
Any and all recently promot'd devils wilt beest did marry bef're a year's endeth to taketh their title, those gents wilt eke produceth an heir to succeedeth those folk if 't be true aught shouldst befall those folk. They then look at Sirzechs with blush and confusion, so Sirzechs explained by stating "Hyoudou Issei, you are hereby ordered to make an heir with Rais Gremory through marriage." he then said with a kind smile "This is my reward to you for rescuing my dear little sister. Also isn't a befitting one at that, since you have many stated a time that her virginity is yours."; Rais and Issei just looked at each still having blush on their faces, them both staring in each other's eyes as if having a silent conversation for a couple of minutes before Issei turned to the devil king and said " I accept your reward".
Meanwhile at the Hyoudou Residence
Asia was making dinner in the kitchen, the rest were in the living room having fun playing games, Azazel and Rossweisse were drinking, she was complaining again about being alone; this was all going on while the parents were on a date night. Asia was humming while she worked, they were celeberating the sucess of their cafe during the festival, so she was making curry with sekihan rice. She stopped humming as she rememberd what her and the rest of the occult club eavesdropped on before they came home, though she was happy for her big sister and for issei; she couldn't help the jealous feelings she has for Rais. She quickly shoock her had at where her mind was going, and thought to herself "I shouldn't feel.this way, if Issei wants her then I should respect his decision, but i will not give up." with a determine look on her face she returned to.her work. Just then everyone heard "We're home" as Rais called out, Asia and the other looked over to the front door as the two lovebirds walked in; they all then came to greet them all asking what took the two so long.
It was then that Asia noticed that they were holding hands and something was glittering on Rais's left hand, "What is that on your hand, Rais Oneesan" Asia asked with a curious look on her face, Rais and Issei shot each other a knowing look before turning back to the rest of the club: " We are engaged!" Rais said with a big smile on her face as she brought up her left hand. On her ring finger was a gold ring with a nice sized ruby in the middle of it, while everyone was telling congraduations to the couple, Asia face just showed how heartbroken she was, but she shooked her head and congraduated the couple. Soon after the gathering of friends were partying for a different reasons, during which Rias pulled the young nun aside; the young girl gaved the girl who she saw as her older sister and thought her as so. Rias looked down at Asia with a concerned face before asking what was wrong, Asia looked around them, knowing two things: one was the president had situated them near the steps, away from the others; two was that if she tried to lie, Rias would just see through them, so she decided to her the truth. She looked to side taking a deep breath before looking up to the older girl and saying that she would tell her after the party, Rias just kept looking at Asia with her concern look before smiling and nodding her head in understanding, cause she knew that Asia would keep her promise.
After the partyOnce the party was over, Azazel and Kiba both flew home after saying goodnight to everyone as well as a final congrates to the couple; everyone was going to bed when Asia noticed that Rias wasn't going into Issei's room. Instead she was giving him a kiss goodnight at his bedroom door before going to one of the guestrooms, Asia followed her and when she opened the door; Rias only had her usaul black panties on. Her school uniform and black bra were already on the floor, Asia quickly stepped in the room and turned to closed the door. She then turned back around, the room looked liked Issei's room before the renovation: directly in front of her was the back wall with a window over looking the city, under it was a nightstand with a electric clock that read 9:30pm on it, in the left wall was a empty closet; to the right of the night sat the bed. On it was a fully nude Rias, Asia imediatly blushed at the sight of her naked president in the pale moonlight, Rais then motion for the young girl to sit with her, Asia ,reading the mood, took off her clothes and sat next to her; Rais then said "So are you going to tell me what is going on?".
The young girl let out a breathe that she didn't know she was holding and said " Im jealous and angry at you and Issei-san. Im jealous that you and he are engaged and I'm angry at him for picking you instead of me. And im also jealous that you are with him." that last part shocked both girls as Asia only meant to keep that in her head, Asia quickly looked and then away from her president's shocked face; she had only just realized that not only did she love Issei, but also Rais. After a couple of minutes of silence, the young blonde turned back to see a face of understanding on Rais's face before Rais closed her eyes and lean forward, kissing the young blonde on the lips; Asia look of surprise at the action quickly turned into bliss as she too closed her eyes and melted into the kiss.
(Yuri lemon start)
Asia then grabbed both of Rais's breast and started to grope and knead them, this made Rais moan into the kiss which Asia then silenced by thrusting her tongue into the other girl's mouth; Rais then grabbed Asia and positioned her to where she was on top of the blonde and then turn the tides by pinching the young girl's breasts. Asia gasp in pleasure and then moan as Rais dominated her mouth, after another five minutes of tongue swirling,sucking, pinching and groping, Rais broke off the kiss, leaving a string of siliva connecting the two; she looked down at the nuaghty faced Asia with lust and love in her eyes. She then lean down besides Asia's head and whispered in her ear " Now its time for the real fun to begun, but do you wwnt you're first time with me or Issei?" Asia just shivered in response before stating "Though I love you, I want my first time with Ise-san." Asia said with a blush, Rias just nodded before saying while her hands move in her usaul way of making a spell "Then I'm going to be taking your anal virginity" she then summoned a red and black double sided dildo and inserted one end in her ass and moaned in pleasure before looking at Asia, who just nodded her head before she felt the object enter her. She groaned in discomfort that Rias tried to take away by sucking on her D-cup breasts and watched as Asia's faced morphed back to bliss, Rais continue to focus on sucking the Asia's right breast, while she used one of her hands to pinch the left breast, when Asia's face morphed back to one of bliss, Rais willed with her mind, the dildo to start thrusting in girls; they both squeezed each other's hands in pleasure before they started to makeout again. Thirty minutes later the two girls screamed out each other's names as they climaxed.
(Yuri lemon end)
Rais collapsed on top of Asia, and then rolled on to her back, both of them heaving and panting as they saw stars; once they got their breaths back, they rolled into their sides facing each other with love and lust in their eyes. "So... what now" Asia asked, her lover just gave her a confused look and asked "What do you mean?" "I mean, what do we do, you and I both love Ise-san, that's why you both are engaged, but I also love you and I assume you love me too, right?" Asia said with worry in her eyes, Rias just gave her a reassuring smile as she gave Asia yet another passion-filled kiss before saying "Yes, I do love you and Issei, and yes him and I are engaged to be married, but the regulations didn't say that he couldn't have more than one wife." "You mean-" Asia asked conspiracy "Yes, Asia, how would you like to be not only my sister in life but in marriage?" Rais asked the stunned girl, Rais waited a couple and was surprised to see prinpicks of tears in Asia's eyes as well as a small smile on the young girl's face; Rais then placed a hand on the small girls waist and pulled her close. With Asia so close that their breasts were pressed up against eachother, Rais then kissed the girls tears away before giving her another kiss on the lips, Asia then said after the kiss "Well I geuss Issei is getting his harem after all." Rais just replied back with "We'll see about that, let's just see how he can handle us." She said mischeousively before they both fell asleep from exhaustion.
Underworld, Gremory, Throne Hallway
Rais and Asia were standing in front of a tall ornate door that lead to the king of the demons, Asia looked over to her lover in worry Rias just looked down to her before placing a hand on the girl's cheek and pulling her into a passionate kiss before saying "Don't worry, everything will be ok; so show me your lovely smile."; the doors opened and the two of them walked into the dimly lit room. They were greeted with the sight of Rias's brother sitting on his throne, once they were only two feet from him, they kneeled before him; "Sister, you know you're not required to do that when other's are not present" Sirzechs said. Rias rose from her position and saw that her brother was right, there was no one else in the room she let out a sigh before saying "Onee-sama, I have a favor to ask of you: please allow Asia to become Issei's second and my sister wife", Sirzechs just looked at her surprised at what she was saying; and then he looked over to Asia. Her face was one of hopefulness and fear, he then said: " Let's see what the young demoness has to say before I give my answer." Asia just looked at Rias, who made a gesture that said 'Go ahead', before turning to her king and stated: "I love Issei, but I also love Rias and if I were to be married to them, I would be the happiest girl ever."; Rias gave the young girl a hug, she was proud that Asia stated her mind. They then looked over to Sirzechs, who had a smile on his face, he then stated: "I will grant your wishes, but just know that I don't know the rest of the Demon World will react." Rias just said in response while Asia made a determined face, "Let them think what they want, I don't care, because I will be with the ones I love." and with that, the two girls left the throne room.
Once he determined that the two girls had indeed left the mansion, Sirzechs removed a spell that had concealed his very naked wife, who was in between his legs; "I thought for sure they would've catched us" Grayfia said as she moves her face away from his length. "They would've if I had lost my concentration from your sucking." He said in response, then he pulled her into his lap, her entrance lightly brushing up against him, "Now, it is time for my payback" before thrusting into his very wet wife; "Oh yes, please give me another child and Millicus another sibling" she moaned in pleasure. Her pleasure-filled screams could be heard all throughout the house on that day.
Meanwhile
While on the train ride home, Asia asked the older girl a personal question: "Rias, how did you know that you were Bi?, Rias just gave her a blushful smile as she answered, " You know how Akeno was the first of my peerage, well for a while it was just me and her because of that we kind of just fell in love but after a bit, we had mutual break-up and stayed as close friends, but that will never." Asia just smiled at the sentiment in the older girl's voice, she then laid her head on Rias's shoulder and fell asleep, the older girl kissed her on the forehead before also sleeping the train ride home.
Sunday A week has since the announcement and it was also six days since the girls' meeting with the king, Issei was standing in front of the altar waiting for his bride, looked around the church: saw his parents, Rias' family, demon, fallen angels, and angel guards in the audience as well; everyone from the occult club was standing on either of the altar. Everyone except for Asia, Issei was surprised to see one his dearest friends not there; he looked over to Rais's maid of honor: Akeno, "Hey, Akeno where's Asia; I thought she would be here to celebrate with us all." "ARA ARA, I shouldn't ruin the surprise, should I?" Akeno said with a knowing smile. Issei was about to ask what she when the iconic march down the aisle song started to play, everyone in the audience stood up (including Rosswiesse, who stopped crying about her woes about not finding a man before her new boss got hitched, Azazel looked trying his best to not look like he knew her.) they all looked towards the church entrance. The doors opened and everyone, except for occult research club, Azazel, and Rosswiesse, were surprised to see two girls were walking down the aisle in matching wedding gowns, the gowns were the exact replica of the dress Rias was wearing in Issei's marriage dream except that Rias was carrying yellow flowers while Asia had red; once they reached him they giggled at him as he had face that was a mix of confusion and dumbstruck.
Issei then turned to the priest when he heard the man clear his throat, he looked to be very uncomfortable, "Probably due to 2/3rd of the people here are enemies of the Church and they are asking him to marry three of them." he thought with a smile on his face that quickly turn to one of shock as realized what he thought as his whole body froze; he only unfroze when he heard Draig telepathically say: "Partner, you better speak up, or the girls will think that they are marrying a statue.", the statement made Issei say yes a bit louder then he wanted it to be which cause audience as well as the brides and bridesmaids to laugh a bit. Once the laughter died down, the Priest then asked for the rings, Gasper handed them the bands and they each placed them on the respective finger: they were simple gold bands with three Gems each. The gems were two rubies surrounding a jade gemstone. The Priest then reluctantly said "Now with the power invested in me by the city of Tokyo, I now pronounced these three Husbands and wifes. You may kiss the brides. " , Issei did just: he first have a quick but passionate kiss to Rias and then gave an equally quick but passionate kiss to Asia as well; once he was done the audience let out with their cheers and applause.
Three hours later
The newly wedded threesome stumbled through the front door of their house, they were exhausted from the reception, especially Issei as Draig gave him a new power as a wedding gift; which Issei used when during the reception they had to do the traditional Bride and Groom dance. When the power activated everyone was seeing double: including Issei himself, a couple of seconds later, Draig address the occult club "This new power allows the user to not only double themselves but also allows the clone to use the gear's power as well." Draig then again addressed Issei telepathically "But the power will only last for fifteen minutes" and with that the two Isseis' each took a hand of their wives and took to the dance floor.
Present time
Issei was now laying on his bed, staring at his wedding ring in disbelief as he waited for sleep to take it's hold as he rolled on his side with his back to the bedroom door. 10 minutes later, he woke to movement beneath the sheets, issei then looked over to the bottom of the bed and saw two large bumps coming along the edges of the bed; he quickly backed up all the way to the head as the two heads of his wives pop out of the sheets, both of them smiling seductively at him. Rais then said with a purr "Aw Issei, why don't just come and play with us." as both pull him back down towards them, the sheets then fell to the floor as Rais position herself just above his face and Asia moved herself in between his legs; before she started to remove his boxers.
His throbbing member, once released from the constraints of the briefs, gently slapped against the young blonde girl. Asia then gave it a good long lick before moving herself to where her pussy was just hovering over his penis for a minute, before plunging herself right on to it; she then let out a scream of pain that was quickly silenced with Rias kissing her right on the lips, trying to take her pain away. When they broke for a breath, Rias then asked her if she was okay, to which the young bonds nodded at before giving Rias a devilish smile as Asia started to slowly bounce on Issei; each time bringing deep inside her than before. Seeing this, Rias thought it was her cue to get Issei to eat her out, "Issei, can you please start licking me?" She asked in a husky voice before feeling his reply as he started to lightly probe at her lips. After about 5 minutes of going slow, Asia then picked up her speed and started to bounce even faster, Issei could only groan at the pleasure he was feeling as well as listen to the wonderful music his wives were making as he started to heavily suck on the.crimson princess's clitoris; and wasn't till a couple of minutes later that the three of them climaxed together.
As they all collapsed on top of each other, Asia was quick to catch her breath and pointed her hands at her other two lovers, summoning up the twilight healing; she then refilled up their stamina. Rias, after feeling her strength return, turned to Issei and asked him with a smirk "Ready for round two" to which he replied back with "Give me a moment" and then proceeded to use his new power to clone him. The girls, after getting off of the first Issei, just looked at the two with drool dripping out of the mouths as they stared at the two large members in front of them; then the second Issei grabbed Asia and flipped her over to where she was on all four with both of her holes facing towards the clone. Asia let out a gasp turned into a moan as she felt him drive his member home. Rias watching this, then mounted the original Issei cowgirl style; Issei groaned at this and said "Rias, you are so tight" before letting out more noises as she started to grind and bounce hard on him, with Issei moving in the opposite directions of her.
15 minutes later of pleasure filled groans and wet smacking sounds, the four of them each called out the other's names as they climaxed; with second Issei actually disappearing as he released. The two girls then collapsed on their respective sides of him (Rias on his left and Asia on his right), they then fell into a blissful sleep.
6 Years later
Koneko collapsed on top of Irina who was already asleep on Rossweisse. Koneko, before falling asleep with a smile on her face, looked around their bedroom at the rest of the harem that included: her sister Kuroka, Xenovia, and Akeno; all four also were naked with a blissful smile on their faces. Koneko's eyes then landed on her husband with his two original first wives as they were naked and sleeping in the middle of the big orgy. She then closed her eyes and dreamed of wonderful dreams with her new family.
So that is it, I hope you all like my take on both the cannon harem and making my own ending for them. Until next time this is Whovian9299 signing off.