Well, perhaps a story where the two characters cross paths due to a serial killer case. The killer seems to be targeting people involved in the legal system, and Perry Mason is representing some of the potential victims or suspects. Ironside gets involved as the detective on the case. Their different approaches at first clash but then they start to respect each other and combine their efforts to catch the killer. They might also discover a hidden conspiracy behind the killings.
Perry Mason is often seen as a bit of an idealist, believing in the power of the law to bring justice. Ironside has seen the darker side of the law and is more cynical. In a crossover, their personalities can blend when they take on a case that challenges both of their views. Maybe a case where the law seems to be failing the innocent due to corruption. Perry's idealism makes him fight even harder, while Ironside's cynicism helps them see the real motives behind the people involved. Together, they can create a more balanced approach to solving the case and bringing about justice.
Another popular one might be 'The Case of the Howling Dog'. The unique premise of the howling dog being related to a murder mystery captured the imagination of many readers. It also showcases Perry Mason's ability to think outside the box when solving cases.
A great storyline might involve a fusion of the two worlds' mechanics. For example, the Velvet Room from Persona could have some connection to Joker's world. The Igor-like figure could offer Joker and his friends some new kind of power or knowledge that they use to combat a common foe. Or perhaps the Persona characters learn about Joker's Metaverse Navigator and try to replicate it in their world, which leads to all sorts of unforeseen consequences and adventures.
Another could be a time - travel scenario where Naruto goes back in time and meets Rikudou Sennin. They then team up to prevent a great evil from ever arising in the first place. This would allow for a lot of character development and exploration of the Naruto universe's history.
One of the most interesting storylines could be the interaction between the different species in Mass Effect and those from Stargate. For example, how would the Asari react to the Goa'uld? The Asari are a long - lived, biotic - using species in Mass Effect, while the Goa'uld are parasitic snake - like beings in Stargate. Another cool idea is the technology exchange. The Mass Effect universe has advanced biotic and cybernetic technology, and Stargate has its own unique wormhole - based travel and Ancient technology. A fanfiction could explore how these technologies might be combined or used against each other. Also, the cultural clashes would be fascinating. The different races in Mass Effect have their own moral and ethical codes, and the same goes for the races in Stargate. How would they deal with each other's values?
One interesting storyline could be Naruto using the Sharingan to enhance his combat skills in a new and unexpected way. For example, he might combine his Rasengan with Sharingan - powered genjutsu to create a more powerful and deceptive attack.
A crossover involving a shared enemy. Maybe a new alien race that is a threat to both universes emerges. The combined forces of Babylon 5 and Star Trek would have to pool their resources. The Starfleet officers could share their scientific knowledge to analyze the new threat, while the Babylon 5 personnel could offer their street - smart combat and negotiation skills developed from their own experiences in the often - tumultuous Babylon 5 station.
A really cool storyline might involve a powerful object or spell that links the two shows. For instance, a magical artifact in 'Supernatural' that can also affect the Wesen in 'Grimm'. The characters from both shows would have to race against time to find and control this object before it falls into the wrong hands. It would be a high - stakes adventure that combines the best elements of both shows, like the family - centered themes in 'Supernatural' and the unique fairy - tale inspired world of 'Grimm'.
A crossover fanfiction could also explore a personal connection. What if a member of the Reagan family was a big fan of Castle's books? And then they end up meeting in a situation where they need to work together on a case. This would add an interesting layer of fan - meets - idol dynamic to the story while also dealing with the crime - solving aspect.
One of the most interesting storylines could be about a character from Skyrim finding themselves in the world of Dragon Age. Maybe a Dragonborn suddenly appears in Ferelden during the Blight. They could use their Thu'um to fight darkspawn in a way that astonishes the people there. Another great idea is a mage from Dragon Age being teleported to Skyrim and having to deal with the different magic system and dragons there.