This is my idea of the relationship between Issei and Irina I know not everyone will enjoy this outcome.
This story is set in the future after Issei has married Rias and has established his harem.
Morning at the Hyodou residence on the Gremory property.
Rias is helping Issei put on large awkward looking white robes.
"Issei you must listen closely to everything that Michael Sama tells you, this is very important"
"I know" said Issei " This is a very big day Irina has been waiting so patiently for this"
"That's right she has lots of fun with us, playing with all of the children but I know she has wanted her own for a long time now. You must remember to thank Onii Sama for convincing Michael to put the request for the ceremony through so quickly, and for allowing them to set up the tabernacle here by the house."
"Yes they have really been too kind, Michael seems to be acting like a grandfather already. I hope that everything will go well with the ceremony"
"If it is Issei I am sure it will be alright, you will do whatever it takes"
Just then the door bursts open and in rushes Asia calling "Issei, Rias are you ready?"
tumbling in after her come four children the oldest a four year old with dark crimson hair yells "daddy" and runs over to hug Issei's legs the three other children stumble over following suit.
"Daddy you are wearing the same clothes as Aunty Irina!" The girl exclaimed turning toward the door.
Irina stood there wearing a white robe similar to Issei's but with lace trim around the sleeves and neck, holding an infant with curly blond hair.
"Good morning" Irina said with a slight blush
"Good morning" said Issei
Rias gently bent over, picked up the little girl and said " Today is a very special day your daddy and Aunty Irina are going to start a ceremony"
Issei turned to kiss the girl on the head "That's right and soon you will have another little brother or sister"
Asia turned back toward Irina gathered the infant into her own arms and ushered the other children out " But you two must get out there everyone is already waiting"
"Let's give them a moment before they head out" Rias said and followed still carrying the girl and gave Irina a quick kiss as she passed "good luck to both of you"
Alone Issei and Irina looked into each others eyes
"I almost can't believe the day is finally here," said Irina "Thank you for being willing to go through this for me... sniffle"
Issei reached over and brought her into his arms "Irina, I love you I would do anything for you. And being alone with you for three days is no burden. Now lets head out to the tabernacle, my wife"
"Yes"
And wrapping his arm around her waist they walked outside.
"You will enter into the tabernacle and for three days you will meditate together. You are not to talk, you are not to move. There will be no contact with the outside. During this time you both will cleanse your minds of any impure thoughts. That goes for you Issei" Michael stood at the door of the tabernacle which was a large white tent erected behind the house. The rest of the Hyodou family stood listening as Issei and Irina prepared to go in.
Xenovia turned to Koneko and whispered "10 bucks says he can't do it"
Koneko shook her head " Issei is an incurable pervert"
Michael continued "If you cannot purify your mind you will not be able to conceive a child without causing Irina to fall and we cannot allow that'
Azazel said"It wouldn't be that bad and it would make all of this easier"
"I do not want Irina to fall and give up what she has" Issei said "I will do all that I can"
"Good, Then to continue this tabernacle has been specially designed to repress the devil and dragon energies without doing you harm, by the morning of the third day you will be infused with a small amount of holy power and be able to complete the ceremony. At which time I will show up,"
"Wait you will show up?" asked Issei
"Yes I will show up, and oversee the conception of the child"
"You will oversee the conception of the child?"
"Yes I will oversee the conception of the child why are you making me repeat myself"
" Why are you overseeing the conception?"
"To ensure that no impure thoughts enter into your head during it"
"It?"
"It"
"It?"
"Yes IT!"
"Sex?"
"Yes Sex!"
"I am supposed to have no impure thoughts during it"
"That is right or else Irina will end up turning or worse becoming defiled"
"It's ok Issei if we can't do it" Irina said as she grasped onto his robe.
"I will do it! We cannot give up now I was just a bit surprised is all"
"Do not worry Issei this Tabernacle was made especially for you it is the most powerful portable holy ground ever created your mind will be cleansed while you are in it" Michael said.
"Ok the three days starts now please enter into the tabernacle and sit on the mats facing each other and begin your meditation."
"Yes Michael Sama" both Issei and Irina bowed to Michael and headed into the tabernacle with no looks back to the audience that was there.
After they entered and the door flap closed behind them a bright white light started to glow from the whole surface of the tent. The glow was visible even in the bright mid morning sun.
"Do you really think they will be Ok, three days is a long time for Issei going without especially as his life is now?" Azazel asked Michael
" He will be fine and I am going to leave another angel here who can sense what is going on inside the Tabernacle and will alert us if anything is wrong."
"Alright but I hope you know what you are doing"
days later a few hours before the ceremony is supposed to be complete at 4:00 in the morning.
"Rias get up something is wrong"
Rias is woken by Akeno and Asia
"What what is wrong?" she asked
"look at the Tabernacle"Akeno said with fear in her eyes.
Outside the tent stood just as tall and stable looking and glowing … a dark red.
"What the Hell" the three of them rushed out to the tabernacle to find out what is wrong. On the way Rias contacted Azazel to come. When they got there the angel on duty, was asleep. Akeno kicked the unnamed minion awake.
"Waah! What is going on? Why did you kick me?" unnamed angel minion asked "Oh hells bells" the angel said as he realized why it was they kicked him awake.
"Why aren't you doing your job, how did you not know this was happening?!" Rias yelled at the minion
" I am sorry I had an alarm set up to let me know if either of them moved off of their mats so thought I could sleep"
"Well what is this?"
"I, I don't know nothing like this was supposed to happen. I could feel some of the Dragons power before filling the room inside but it had been subsiding over the last two days. Now it is like there is nothing other than dragons power the Holy power has been overwhelmed! It is gone!"
"Oh no, Irina." The three of them started to run inside.
"You can't go in there we don't know what is going on, This tabernacle should have been able to suppress a god level demon for three days, this power is insane."the angel stood to block their way.
"Get out of the way!" Rias, Akeno and Asia all struck at the same time Rias with her power of destruction Akeno with a bolt of lightning and Asia with her fist, (she actually threw a healing in there to make sure they guy didn't die but he was seriously knocked out.)
As they ran into the tabernacle they saw Issei and Irina in front of them. Issei was sitting still on the mat eyes closed but Irina was collapsed on the floor sweat covered her whole body as she panted uncontrollably.
"Issei stop!"
The three shouted and as they did Issei opened his eyes. An enormous red been of light shot out of his eyes landing on Irina for a second and then started to dim. He turned his head slowly the light almost gone from his eyes and as he saw them he whispered "Rias... Irina... help" and then collapsed as well.
Next Day
"How are they"
"All of them seem healthy, they are just resting now"
"That was quite a shock, I can't believe such a thing could happen."
"I have learned not to underestimate the power of the Chichiryuutei"
"So do we know how this came about."
"We think that because Isseis power comes from ecchi things when he attempted to suppress all of that it actually began to build up until it became overwhelming"
"But to think that he would impregnate a girl just by looking at her!"
"Yes, and I thought that was only a saying but he has made it true the Chichiryuutei that can impregnate an angel with a glance!"
"But then what is the reason for the growth?"
"Well when Rias and the others came into the tent it was already bathed in the power of the dragon which had been going since the beginning of the ceremony. When they ran in to get her the baby started to grow visibly inside her and within a few minutes she was ready to give birth, this must be because she had absorbed so much of the dragons power in that time it poured into the child and it grew to accommodate the power."
They looked into the room where on the bed lay Issei with his arm around Irina as their new born son lay on top between them.
"That child must be destined for an interesting life"
After that Irina and Issei could have sex all they wanted because Irina had a bit of dragon left in her from all of the power she absorbed so she didn't fall when they have sex ( the dragon part protects her angel part from the pervyness)
