It could involve the different art styles of the two series. For example, the 2003 version has a more angular and detailed look compared to the 2012's slightly more rounded and colorful style. Maybe in the fanfic, the turtles from each version could meet and be confused by the differences in their appearances.
One aspect could be how the different power systems work together. In Man of Steel, Superman has his Kryptonian powers. In Game of Thrones, there are different forms of magic. A fanfic could explore if Superman's powers could interact with the magic in Westeros. Maybe his powers could be enhanced or weakened by it. And also, how would the people of Westeros react to an all - powerful being like Superman? Some might worship him, while others might see him as a threat to their power and status quo.
A crossover between Batman and Aphrodite could be really interesting. Maybe Aphrodite could use her powers of love and beauty to influence Gotham. She might make some of the villains fall in love with the idea of being good. For Batman, it could be a struggle as he's used to dealing with things in a more practical, non - magical way. He'd have to figure out how to deal with a goddess in his city.
One possible plot could be that the Teenage Mutant Ninja Turtles somehow end up in the Freddy Fazbear's Pizza place. Maybe they are investigating some strange disappearances that are rumored to be related to the animatronics. They could use their ninja skills to navigate the dark hallways and face off against the haunted animatronics. The turtles' unique personalities would add a fun dynamic, like Mikey being scared at first but then finding the whole situation exciting, while Raph is ready to fight from the start.
One possibility could be that Ichigo's unique powers as a Soul Reaper and his transcendental forms could create an interesting dynamic in the DxD universe. Maybe his Hollow powers would be seen as a new type of 'evil' power there, and the devils would either try to recruit him or fight him. Also, his Bankai and its evolutions could make him a formidable opponent against the various factions in DxD.
Well, it could involve Iron Man's technology merging with Transformers' mechanics. Maybe Tony Stark could find a way to integrate Autobot or Decepticon tech into his suits. For example, he could use Transformer energy sources to power his suits more efficiently.
Well, it could involve the characters from both universes teaming up. Maybe Joel and Ellie from The Last of Us could meet up with Nathan Drake from Uncharted. They might go on an adventure together, like exploring some ancient ruins filled with infected in The Last of Us world while also dealing with the typical Uncharted - style treasure hunters. It would be really exciting to see how their different skills and personalities interact.
Well, it could involve the unique characters from both universes meeting. For example, the Jedi from Star Wars might encounter the Vault Hunters from Borderlands. They could team up to fight a common enemy, like a Sith Lord who has somehow made his way into the Borderlands universe and is after the Vaults. The Force powers of the Jedi would be an interesting contrast to the high - tech weaponry and skills of the Vault Hunters.
It could merge the main story arcs. For instance, if the 2012 turtles are facing a big threat like Kraang, the 2003 turtles could come in and offer their combat experience. Their different fighting styles would make for some exciting battle scenes.
It could entail exploring their different power sets. Violet has her superpowers which are more physical - based like invisibility and creating force fields. Raven, on the other hand, has her magical powers. In the fanfic, they could train together and learn new ways to use their powers. For instance, Raven could teach Violet how to use her powers in a more offensive way using magic, while Violet could show Raven how to be more strategic with her force fields in combat.
Maybe the Loud siblings could be transported to the TMNT universe. The boys would be fascinated by the Turtles' ninja skills and gadgets, and the sisters could use their own unique skills to help the Turtles in their fight against the Foot Clan. For example, Lola could use her pageant charm to distract the bad guys, while Lincoln could bond with the Turtles over being part of a big group.