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.
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.
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.
Harry Potter himself could be the main character. He could be the one who stumbles into the world of Bioshock. His magical abilities would be put to the test against the threats in Rapture.
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.
Yes, there might be such a fanfiction. Fanfiction often takes existing universes like Harry Potter and combines them with other concepts, in this case, Spider Splicer. However, I'm not extremely familiar with this specific one. It could potentially explore a scenario where Harry Potter has some sort of connection or transformation related to Spider Splicer, perhaps in a crossover setting where the magic of Harry Potter meets the more science - fictiony elements of Spider Splicer.
A plot could involve a wizard from the Harry Potter world accidentally stumbling into the Sekirei world. He discovers the Sekirei system and realizes that there are similarities between the magic there and the magic he knows. He then teams up with a Sekirei and they try to find a way back to his world while also getting caught up in the Sekirei battles and politics. Along the way, they learn from each other's cultures and magics, and perhaps even find a way to use the two magics together to overcome various obstacles.
Maybe Harry Potter, as a ghoul, has to hide his true identity from his friends at Hogwarts. He might struggle with his newfound nature while still trying to fight against the dark forces in the wizarding world.