So for a while now I've been wondering and imagining how High School DxD would end, but that made me realize, I don't want High School DxD to actually end. This is why I thought that I'd create my own ending that can be as crazy and amazing as i could personally come up with.
So in my ending, I envision a massive simultaneous wedding between Issei and all the girls in his harem, Kiba and Gasper (as females, because why the hell not), and all the other girls that have fallen for him (like Tsubasa, Kiyome and Kunou, and maybe others in the future, who knows). All the Devil families are attending because its such a grand occasion, as well as the Angels and even some humans because I envision that peace has been achieved to the point where all beings are aware of each other and can co-exist. And as the moment comes to a close where Issei is about to say his "I do's", the wedding is crashed by any and every antagonist to-date (at least ones that haven't turned good [and to hell with plot, because everyone is back.. dead or alive, past, present or future]) and they have come for revenge against Issei and the various heroines. Instead of everyone fighting the intruders, Issei and the girls declare that this is their wedding, and they will not allow anyone ruin it and they set off on one last fight.
I'll spare the details of the fight, you can imagine that on your own, but expect lots of explosions and destruction, and the obligitory numerous Oppai being exposed left and right, ending in the grand victory of Issei and his brides-to-be.
Once all the dust has settled, the girls decide that they won't end this until Issei has said his "I do", and with overwhelming persuasion (or pressure, same thing), he gives one final look at them, panning from left to right, right to left, he says it.. "I Do"..
Tears overwhelm all of the girls as they all rush to hug and hold their now husband, Issei.
Behind them all of the Devils, Angels and Humans give them an enourmous cheer and grand applause, congratulating them on their union.
And fade to black.....
Well that has been my grand ending to High School DxD, so I encourage you to come up with your own endings, no matter if they are as plain as white bread or as awesome as an Undead mad scientist with an electric guitar riding a robo T-Rex with rockets strapped to it on top of a giant shark with lasers that swims on top of rainbows... But getting back on topic, have fun with it and tell me what you think of the ending I came up with.