The fight scene here will just focus on the one on one for (Y/n) and Kokabiel
3rd POV
Akeno plummeted to the ground after saving Rias from Kokabiel blowing her into oblivion "Akeno!" Issei said lunging to catch her but he was just a little too slow "Gotcha" (Y/n) said catching her "(Y/n), how are you even moving?" Akeno said as he put her down "Let's just say, it probably would have hurt me less if I just let you land on me instead" he said holding his stomach and he glared up at Kokabiel "I would have thought your injuries would have been fatal, very impressive, for a low level devil" Kokabiel said as (Y/n) grew a cocky grin "Listen asshole, better have tried and none have succeeded" and Akeno looked up at him with a slight blush on her face "First you attack me, that I'm okay with, now you attack my friends and that isn't ok, now your taking the school that we go too and good sir I just have one thing to say" and (Y/n)'s balance breaker came around him with black fire at his feet and his red eyes glowing "I'll make you pay for every inch with your own blood" and the flames got more intense and some came out of his back. The flames on his back burnt out and revealing a pair of black dragon wings that were folded up on (Y/n)'s back "Oh come on, now he gets wings that's so not fair!" Issei said as (Y/n) launched off the ground up the the fallen angel 'Off to go save us again, I think I've grown more fond of him too' Akeno thought looking up at the two.
(Y/n) POV
I came up to Kokabiel and we were about 30 or so feet from each other "You really think some visual change is going to allow you to beat me?" Kokabiel said with his twisted grin "Yeah and when I'm done I'll personally rearrange your internal organs" I said and eh shot a light spear at me bu thanks to my new mobility I easily avoided it as it flew past me. I charged a dragon shot and I blasted straight at him but he just smacked it away "After all that talk you still can't lay a finger on me" he mocked "Just getting started" and Kokabiel summoned a spear of light in his hand, one that was bigger than the last one. I charged a shot and I fired it straight at him, it wasn't in an attempt to kill him but just create a smoke screen while I rushed forward. I kicked him straight in the stomach making the spear dissipate and he flew back ten feet. I tried to follow it up with a right hook but he caught my first like it was nothing "To think I actually thought you could put up a fight" and he threw me straight towards the ground. I skipped off the ground and smashed through a wall "(Y/n)!" I heard Rias say and she ran towards me while I hustled myself up again. I used the wall to hold me up since I could barely stand on my own two feet "Rias, get back" I tried to warn her but the ground next to her exploded "Rias!" I called out as Asia got to her first. She was alright but none of us could take a hit like that again. I saw Kokabiel on the ground with Kiba and Xenovia attacking him with their new swords and I clenched my fists in frustration 'Damn, even though I just got a large boots to my power, it isn't enough' I thought as I fell onto all fours "The Black Dragon brought to his knees? How pathetic" Kokabiel said with a sick grin on his twisted face "I need more" I said to myself "I can give you more" I heard Revenant say "it's a long shot but it should give you enough to beat this guy" "I don't care, give me it" "Fine"
3rd POV
(Y/n) stood up holding his stomach with his left hand "You can barely stand up, yet you still get up, I should just kill you to end it" Kokabiel said as he held up another spear of light "Not just yet" (Y/n) said and held up his right arm. His boosted gear grew another purple gem and more silver spikes on his arm "Explosion" his gear said activating his over-booster. A black orb started forming in his palm but it was different than a dragon shot, this started sucking in air violently and everyone's hair was blowing towards it "What is that?" Issei said covering his eyes "Look, the shadows are bending towards it" Asia said as her own shadow came to the orb. It got large enough to fit in (Y/n)'a palm and a swirling black aura went around it "Black Dragon" (Y/n) said as it grew a bit larger "Dark Nova!" he shouted throwing it like a ball. (Y/n) felt his shoulder break from throwing it but he put as much power into it as he could. It impacted Kokabiel but he blocked other a spear and it sent them flying and when they hit the ground a few hundred yards away there was a terrific explosion of white and black fire. (Y/n) dropped to a knee and was breathing heavily while holding his right arm. He came out of balance breaker and Rias hugged him tight "I'm so happy your okay" "Well, okay would be a stretch but yeah, I'm good" he said as Issei came over "How come you get wings now and I don't?" and (Y/n) chuckled at him "Think of it as another step on your climb to over take me" he jokingly said as the trees in front of them all came down "Umm, I don't think he's dead" Issei said as his own gear boosted "I don't have enough strength to make another one of those" (Y/n) said as he glared at Kokabiel as he flew back above them. The Fallen angel laughed at them "That was some show, it was certainly a sight to behold, to bad it was nowhere near enough" Kokabiel said as the top of the dome shattered and a blue light came down "Kokabiel" a voice said as the blue light descended only to reveal it was a balance breaker, a scale mail, a white one at that. "What?" Kokabiel said shielding his eyes from the light "My orders are to bring you too Azazel, by force if necessary" the voice said as the dragon came to an equal level with the fallen angel "I'll never go with you" he said making a huge spear of light, bigger than all the others. The white dragon held up his arm and his blue gems glowed making the spear shrink in size till it's nothing "My sacred gear, divine dividing, it halves the power of the target and gives that power to me" he said as Kokabiel started to throw more randomly but the dragon flew forward and hit Kokabiel smashing into the ground and came back up and flew around a few times.
(Y/n) POV
"Ddraig" my gear said out loud for everyone to hear "Yes Revenant" Issei's gear said back "You wanted to meet your opponent, there he is" my gear said as the bright blue light returned "Azazel!" Kokabiel shouted as they vanished in thin air "That was?" Issei asked me "Yeah, that was the white dragon, your destined opponent" I said and I chose this moment to take a nap.
Time skip
I woke up in my bed with my arm in a brace to keep it from moving "Ow" I said from it still hurting a bit. I had the bed to myself so I'm guessing that Rias must be doing something since I'm alone. I laid back down and thought 'I'm going to sleep for a million years' and I slipped into a deep sleep so I can get ready for the next adventure on the horizon.
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I added Akeno to the pairing since Serafall isn't around that much so now y'all have three
I also may or may not have future additions to the pairing later as well.
