God succession system

Rias stood at the back of the auditorium, waiting for the ceremony to start, and reminiscing about the last three years, the last year especially. She recalled how it wasn't long after starting high school she met Alex, thinking he was simply a delinquent. She then grew interested in him after he defended some of the girls in the school, and tried to scout him into her peerage.

From there her life with him snowballed, he "scammed" her into becoming his girlfriend, then after two years he revealed all of his secrets when he saved her from a life as Raiser's pet wife. She then joined his peerage, and gave all of herself to him. After that her life just continued to become more intense, from fighting Kokabiel, to start of the Khaos Brigades attacks, to even facing off against a god and a god killer.

Then after a few more conflicts, she thought she lost the person she dedicated her everything to, when he got infected with Samael's poison. Not only did he come back to her then, but he even singlehandedly ended the disaster the devil world itself was experiencing. Then he fought the evil dragons, helped the vampires, and even fought to overcome poison once more, this time was that of Yamata no Orochi, and he even gained the ability to be almost immune to poison after that.

Rias was brought back to the present when the ceremony began. She started walking down the center of the auditorium with the rest of the seniors, including Alex, Akeno, Sona, and Tsubaki. As she walked, she heard the applause of those who came to support them, their family and friends. Rias saw her father and mother standing there, while he recorded her with a camera. Barakiel was crying as he watched Akeno walk, much to her shame, and Serafall tried to make a big uproar for Sona, before she sent a stern look at her older sister.

Then Rias saw her own older sister, Grayfia, along with her nephew Millicas. They stood alone, to the side, and Rias was saddened when she thought of the reason, and the events leading up to it.

After recovering from the poison, they went to heaven to have Ascalon fixed. Alex then requested a talk with the miracle child, Teodoro Legrenzi, in order to come to an understanding before he started a revolt. Though Teodoro refused to listen at first, Alex offered an alternative of him fighting two exorcists of Teodoro's choice. As a result, he faced the two veteran exorcists Vasco Strada, the former wielded of Durandal, and Ewald Christaldi, the former wielder of several fragments of Excalibur.

Though neither was able to stand up to Alex independently, both were able to stand toe to toe with him until he activated draconian form and increased the gravity in the area. After the fight, Alex then presented Teodoro with files of dozens of devil children that had been orphaned as a result of church hostilities in the past, to show he and the rest of the church weren't the only ones to suffer the previous wars. After that those that wanted to revolt in the church quieted down a bit.

After that they were lured to a specific area in the underworld, just to witness Rizevim and Euclid escape once more with trihexia and the evil dragons Apophis, Níðhöggr, Aži Dahāka, and the user of incinerate anthem Walaberga. Leaving behind Grendal, Ladon, and Masaomi wielding the sword with Yamata no Orochi. With both Kuroka and Koneko armed with Alex's sacred gear jewels, they managed to seal Grendal, and Ladon, while Irina fought and purified Yamata no Orochi with the Hauteclere she received from her father on Christmas, and Masaomi was taken into custody.

A few days later they responded to trihexia attacking every faction simultaneously, by splitting into seven different bodies, with a different person leading some of them at attacking. Alex responded to the one attacking Japan, that also had Rizevim and Euclid both with it. He fought with the both of them and the single head of trihexia, killed Rizevim and Euclid while he also recovered the holy grail.

However the recovery capabilities of trihexia were simply too much for Alex. He powered up as much as possible, and threw every attack he could at it, but it regenerated every time. He even used an attack he called a "Kamehameha", but it still regenerated. He almost went into juggernaut drive, but her brother stopped him before he could. They then enacted a plan to seal several high ranking members of each faction with trihexia, and fight it within a sealed space, that none of them would be able to leave until it was dead.

Grayfia was then forcefully knocked out, and left behind by her brother to stay with Millicas. The ones gone were her brother Sirzechs, Falbium Asmodeus, and their peerage minus their queens. Michael and Raphael went along with their brave saints, minus their aces. Several major gods like Odin, Thor, Zeus, Poseidon, and many more. Finally from the Gregory side only Azazel went.

Rias was then brought out of her thoughts once more, when it was time for them to get their diplomas. Then Xenovia started giving her speech as the next student council president, and was followed by Sona giving hers as the former president. Once she was done, the entire audience in attendance erupted into applause, as the graduation ceremony was finished.

The rest of the day passed in a daze for Rias, as she was congratulated by everyone around her, especially her parents. She was then surprised when instigated by Kiba, he Koneko and Gasper referred to her as "big sister" for the first time, as she was no longer their president.

That night they had a small party with all of those involved in this town, her and her peerage, Sona and her peerage, Ravel, and Irina. After that, she and Akeno dragged Sona and Tsubaki upstairs, to prepare for their own "celebration" with Alex. Even though it was four against one, they of course still lost. And Alex didn't let them go until it was sunrise, even poor Tsubaki even though it was her first time. Before she fell asleep, Rias watched the sun through the window, and couldn't help feeling as if the first chapter of her life was officially done.

(A.N. As I said I'm just skipping to this part, and gave a rough summary of what happened since the fight with Masaomi and Yamata, while I also tried to incorporate it into the story. From here it's the Azazel cup, and then the next world.)