Well, it could be about Harry Potter somehow ending up in the Bioshock world and becoming a Splicer. Maybe he has to use his magic in new and strange ways to survive among the chaos there.
The plot might involve Harry's struggle with the Splicer's madness while still retaining his own identity from the Harry Potter universe. He could be trying to find a way back home and in the process, he might discover some new powers or make new alliances with the characters in Bioshock. For example, he could team up with a Little Sister to fight against the more deranged Splicers.
In this fanfiction, perhaps the magic in Harry Potter's world is seen as a new form of 'plasmid' in the Bioshock world. Harry, as a Splicer, might be hunted by the Big Daddies while also being chased by Voldemort's forces that have somehow also entered this strange new world. He has to balance his two 'natures' - the Splicer with all its mutations and his wizard self, to overcome the multiple threats and find a way to restore order to both his world and the Bioshock world.
Dumbledore, if he were to be in this world, would likely be a guiding force. He would try to understand the moral implications of the Splicer situation. He might see it as a test of character for the students. The Death Eaters, if they were also in this world, could potentially use the Splicer technology to their advantage, becoming even more dangerous adversaries. The Hogwarts professors would be trying to keep the students safe and teach them how to use their skills in this new and dangerous place.
Well, it could be that a dark wizard in the Harry Potter universe discovers the ADAM and plasmids from Bioshock. He starts using them to create an army of super - powered Death Eaters. Harry and his allies have to figure out how to counter this new threat. They might travel to Rapture to find a way to neutralize the ADAM or find some kind of magical antidote. Harry could use his Patronus charm to fend off the more deranged splicers, and the Weasley twins could use their prank - making skills to mess with the Big Daddies.
You might expect a lot of creativity. For example, Harry could have the ability to climb walls like a spider. His magic could be combined with spider - like features. Maybe he could spin webs using his wand or some newfound power. It would be a strange but interesting blend of the magical world of Harry Potter and the more mechanical or biological aspects of Spider Splicer.
It could be an interesting concept. It might imply a crossover in the minds of fans where the world of Harry Potter somehow intersects with the ideas and themes from Bioshock in a way that is related to a character named Ryan. However, it also seems rather strange as the two universes are very different in nature.
Well, in a 'Kagome meets Bioshock' fanfiction, Kagome could be brought to the Bioshock world due to a strange magical anomaly. She may find herself in Columbia instead. There, she'd encounter the zealous citizens and the Vox Populi. Kagome's archery skills could be useful against the Motorized Patriots. She may also try to understand the complex social and political situation in Columbia, all while trying to find a way back to her own world.
The plot could involve a situation where a new form of dark magic is unleashed in the wizarding world, which spreads like wildfire and causes destruction similar to 911. The Ministry of Magic is caught off - guard. Hermione, with her vast knowledge, starts researching a way to counter this magic. Meanwhile, Ron and Harry lead the effort to protect the civilians. They set up shelters in places like the Room of Requirement and use Patronuses to guide people to safety. As they dig deeper, they discover that this dark magic was a planned attack by a long - hidden dark wizard group who wants to take over the wizarding world.
The plot might involve Harry Potter traveling to a world inspired by Bioshock, where he meets characters influenced by Ryan. He could be faced with the same moral and power - related dilemmas as in Bioshock.
A plot could involve Voldemort learning about the power of ADAM in Bioshock. He sees it as a way to gain ultimate power and sends his Death Eaters to Rapture to steal it. Meanwhile, a group of Aurors follow them, and then there's a three - way battle between the Aurors, Death Eaters, and the denizens of Rapture.
Well, perhaps Naruto could find himself in the world of Bioshock. He might initially be confused by the strange environment and the concept of Big Brother. Maybe he would start using his ninja skills to fight against the oppressive forces that Big Brother represents, all while trying to understand the new rules of this world.
A possible crossover idea is the combination of the House system from Harry Potter with the different factions in Bioshock Infinite. The characters might be sorted into groups based on their beliefs, much like in Hogwarts. It could lead to some really unique interactions and storylines as characters from different 'houses' or factions interact.