It's being 25 years since the final fight against Antares. Me and my family decide to retired as Assassin's and left the Brotherhood in great hands, we met a lot of new supernatural friends, help with some of the technology the devils were creating.
I became friends with Ayuka and Serafall, help them in some of their problems and told them that if they felt that to much paperwork was getting hard to handle they could hire people from the brotherhood to help them. Serafall and Sirzechs jump in first at this, Grayfia hit them both but was happy that someone else made them get help from friends.
I help Rias peerage get over their traumas, help Kuroka clean her name and get her to unite with her sister. Issei and Vali became friends/rivals after a heated discussion about boobs and asses, but they still have their dragon rivalry from time to time. Gasper got cure from his agoraphobia once he got reunited with Valerie.
After all that I decide it was time to come clean to all my friends and family that I first build trust in them and told them about how I die in my past life and how I got reincarnated into this world. I left out about this world being a book story since this could cause a crisis in the whole world.
I spend the rest of my life with my 2 beautiful wife's, sometimes I went and visit the brotherhood to check how they are doing and give some advises to some of the masters and mentors, I visit the Cullen's a few times and discover that we all started to age after we pass the age of 500 so all the old vamps decide to get together and start making plans for their families and their futures.
Its being 55 years and even when I felt sad by the news that some of my friends and family pass away I stay strong for those that are still suffering from their lost. In a way I became a counselor to them and everyone around me. I visit some of the supernatural pantheons and have some drinks with a few gods. since I was feeling alone since both my wife's pass away I start dating once more and once again find new mates. Yasaka being my lion side mate, Rossweisse being my vamp side mate and the new one that I never saw it coming Kuroka from my bat side.
Right now I'm in bed looking at my new family and some old friends that came to say their goodbye's to this old man.
"Thanks for coming everyone, I will miss all of you and miss my children and grandkids. To my old friends, please keep my family safe and protect them like I once did. I already informed the brotherhood about my passing and they will stay active for a few more years before they go with everything I have stated in my will inside the brotherhood family vault. Kids remember to always pay attention to your loved ones and protect them till the end." I finished telling them.
We decide to have a big dinner, during or last dinner I sat on my own throne chair and looked at everyone with a smile on my face.
"Remember everyone this is just the beginning of a new adventure not just for me but for everyone in here. And if conflict start once again remember... "To say that nothing is true, is to realize that the foundations of society are fragile, and that we must be the shepherds of our own civilization. To say that everything is permitted, is to understand that we are the architects of our actions, and that we must live with their consequences, whether glorious or tragic." and with those word I close my eyes and pass away with a smile plaster on my face.