Haha true and plus with this complex verse I can create various possibilities and I can change a lot of aspects since these verses are fused together so some changes have to happen.
These verses are fused with MHA:
Lelouch and Nunnally were exiled to Japan by their father the Emperor of Britannia where they still sorta grew up with Suzaku but they soon had to leave since they are still royal children and since due to political issues of the invasion of Britannia when they attacked Japan had failed causing great impact to the world since now Japan was not controlled by Britannia. Muriel now in Japan soon found the two and raised them since her husband Huston passed away and she along with Courage the Cowardly Dog is trying to take care of the young Britannian royal children. She also has Sayoko Shinozaki the ninja maid that helped Muriel and Courage as she also began taking care of Lelouch and Nunnally making sure they are all right. The concept of Courage the Cowardly Dog was a thought that seemed sweet since Muriel and Courage would be interesting since they are living with Lelouch, Nunnally, and Sayoko Shinozaki. The Code Geass characters exist in this verse but are different due to Japan having a force that repelled Britannia due to the fact that Charles Zi Britannia screwed up and began a Cold War with Japan. Also cast members of Code Geass are involved but they are now completely different due to the existence of quirks and the fact that Hero system was created and that Britannia never took over Japan. Somewhere in Japan, now free C.C is watching over Lelouch feeling interested to create a contract with him.
Somehow Jellal, Erza, Ultear, Millianna, Kagura, Gray, Juvia, Natsu, Lucy, Laxus, Mira, Gajeel, Levy, Wendy, Lyon, Sherria, Meredy, Lily Panther, Happy and Carla arrived to the present since Fairy Tail happened in the past about many centuries ago and they appeared in the MHA fusion world, which is the future. Jellal soon found out that he is the distant ancestor of the Robotnik Family making him the ancestor of Gerald Robotnik who passed away 50 years ago due to Britannia not the United Nations or G.U.N like in the Sonic canon attacking the Space Colony Ark. Jellal and the others are now going to try and adapt in a futuristic world on a space ship, and Jellal was given power over the Ark and by accident he released Shadow from his prison who was instead placed safely somewhere in the Ark by Azmuth the creator of the Omnitrix. The reason why Jellal was able to release Shadow was because Jellal is Gerald’s ancestor. Gerald Robotnik begged Azmuth to help him since he needs help to plan a way to stop the Black Arms and since it was from a friend’s request as Azmuth agreed and began various planning to help with Gerald’s plan to stop the Black Arms. Though Jellal would one day in the present thanks to Paradox sending him along with the others to the present for a reason to activate and release Shadow but after awhile Shadow realised that Jellal is a decent person and they both developed a kind bond with each other. The Fairy Tail cast have their magic like in canon since they are from the past and they cannot gain Quirks nor can their magic be stolen or depowered by Anti-Quirk weapons.
This verse has various Sonic the Hedgehog characters as such with the Gerald came into contact with both Black Doom and Azmuth at various points and they managed to create the Ultimate Life Form, however Azmuth was suspicious on how Gerald was acting since he doesn’t know about Gerald’s involvement with Black Doom. Gerald had used Black Doom, and his own DNA but the body had no form, as this was left unsure though Black Doom left and told him that in fifty years he will need Shadow’s help as he vanished. Azmuth however realised what happened and put his own DNA into Shadow and argued with Gerald but they managed to reach an agreement on how to stop Black Doom since he told Azmuth with his DNA he would be able to reject Black Doom’s control. Azmuth decided to inject his own DNA along with a mutated combination of Echidna and Chaos’ DNA to further power Shadow. Now with Shadow released his form a hedgehog since Gerald was inspired by a prophecy of a hedgehog saving the universe from a calamity he lived in peace with Maria and Gerald though Azmuth had to leave due to finishing creating a device that will bring the universe together and it was called the Omnitrix. Though sadly Britannia attacked and Maria helped Shadow hid in the capsule where at this time Azmuth arrived and helped her hide Shadow somewhere and he used a machine where an ancestor of Gerald or Azmuth himself can release Shadow thus making sure he is safe from Britannia. Of course that was 50 years ago and in the present of this fic, Julian Kintobor Robotnik or rather taking the name Eggman is a scientist of Britannia and he is fighting the Freedom Fighters, which have Sonic, Tails, Amy, Sally and many others who rebel against Britannia. Knuckles still remain alone on Angel Island after the whole Death Egg situation, this means he is without much contact due to him being more paranoid with the surface world and he built more traps using lost Echidna technology making sure Eggman and Sonic couldn’t trick him. Though Knuckles and Sonic did team up to stop Eggman but they remain tense allies and thankfully thanks to the Echidna technology found and hiding the Master Emerald inside a shrine this means it was not shattered so Chaos was never released. Rouge the Bat is working for Britannia as a spy and seems to be on another side. Sonic, Tails, Amy, The Chaotix, Sally and Knothole Freedom Fighters teamed up to stop Eggman from trying to destroy Green Hill Zone, gaining the Chaos Emeralds and finally trying to capture Angel Island. Sonic and the others live in South America where Britannia has less control over since most of South America is filled with the Mobians, the Mobians were genetically altered animals due to exposure of Chaos Energy from the Chaos Emeralds itself and the first ones were the Echidna and soon other races thus creating a whole new sub species.
Touma Kamijou from the light novel and anime series A Certain Magical Index appeared and saved Muriel from an assassin quirk user and he began helping her out where he grown a friendship with Lelouch and Courage where he too like them became an over protective big brother figure to Nunnally. He also has his Miracle Breaker and that various characters from his world exist in this mega crossover but in different circumstances. Esper Powers are an offshoot of Quirks and are in the same category as Quirks but are slightly different since they came a decade ago while Quirks came 200 years ago. While the magic in the series are remnants of the Fairy Tail world and BlazBlue magic that was used to create a very different form of magic in the 19th Century. Magical Index verse is fun to do since Touma, Index, Misaka and Accelerator are in this fusion world but are different due to various different circumstances. Accelerator is now just a vigilante fighting people to prove he is the strongest, Misaka is busy studying in a hero school hiding her Esper powers as a Quirk and Touma is considered quirkless due to the oddity of his ability (since in the canon series he was considered weak because of the fact no one knows about his Imagine Breaker). Index however is still being chased by various groups and ended up living with Touma.
For BlazBlue it is seems complicated but this story is going to have some characters from the alternative timeless to the main BlazBlue series such as having Bloodedge Experience and XBlaze series put into this fusion world. In the Bloodedge Experience world: Naoto Kurogane, Raquel Alucard, Hazama (Alternative version), Saya Terumi, Relius Clover (Alternative version), Valkenhayn (Alternative version) and Clavis Alucard (Alternative version). This combined with the XBlaze world from BlazBlue: Es, Tōuya Kagari, Sechs, Jubei (Alternative version), Nine the Phantom (Alternative version), and Celica (Alternative version). In this verse Naoto Kurogane decided to become a hero and he kept his mother's maiden name to distance himself from the name Terumi since his little sister Saya Terumi murdered the family and was sealed away by the magical Amanohokosaka Clan who was related by blood to the Terumi name. Naoto was still bitten by Raquel when he was nearly killed and made into a half vampire and still met with Clavis Alucard where in the main timeline Naoto didn’t get killed by Clavis nor did Saya get "consumed" by Naoto creating a way to create a Fifth Prime Field the mother of Ragna, Jin and Saya. Naoto now reaching sixteen years old wanted to be a hero he joined a hero school and he soon was dragged into the hero world. He soon encounters various people like the couple hero duo Es and Tōuya who are a well-known hero team in Japan that secretly uses magic from an old magical family such as the Amanohokosaka Clan. He soon finds and befriends Konoe aka Nine the Phantom a hero who uses magic where one knows and thought she is a Quirk user, and her husband Jubei the sword hero who is a Beastkin who existed in the mountains of Japan and her younger sister of Celica the healing hero who uses magic like her older sister. He soon encounters the mystery team Hazama, and Relius Clover, and finally the vigilante Sechs. Though sadly he soon has to face his evil little sister Saya Terumi who hunts for souls due to her drive Soul Eater.
For the Fate series it follows Fate/Stay Night but in a different way since Mage Craft still exists but less around since the development of quirks and Mages with Magic Circuits CANNOT have quirks thus making them seem quirkless to the world. Shirou Emiya exists in this fic, as this is he before the Holy Grail War where he is only good with Projection magic and is determined to be a hero. Fate/Zero happened but ended slightly different as the grail did destroy Fuyuki City but Kiritsugu Emiya managed to get enough force to destroy the Einzberns and take Illya away from the Einzbern House, he along with Zelretch managed to end the Holy Grail War permanently by dismantling it. He moved to Japan with Illya and takes Shirou in adoption and after many months Kiritsugu Emiya passed away leaving Shirou to take care of the house and protect Illya, he is an also good friends with Rin Tohsaka, Sakura Matou and Luviagelita Edelfelt. The Matou Family was destroyed when Clavis Alucard found out what Zouken is trying to do and ended up killing him and destroying the house leaving Shinji to be raised by his drunk father and for Sakura to remain living with Shirou but keeping the Matou name. Also the remains of the Holy Grail War of some sort might appear though slightly different since Gilgamesh is still around.