Who could be the main antagonist in 'Loki kidnaps the Hulk' fanfiction if not Loki?

Well, perhaps Loki kidnaps the Hulk to use his strength in some scheme against the Avengers. Maybe he wants to use the Hulk to break into a secure location or as a weapon against Thor.

It could be another powerful deity from either the Norse or the Christian pantheon who doesn't want Gabriel and Loki to team up. Maybe a more rigid and traditional angel who thinks Gabriel is consorting with the wrong crowd by interacting with Loki.

An interdimensional being that wants to use Loki's unique connection to different realms. This being has the power to manipulate time and space, making it extremely difficult for the Avengers to reach Loki. The Avengers would need to figure out the being's weaknesses and use their own combined powers and skills to overcome it and rescue Loki.

It could be Malekith. He might see the sister as a way to get to Thor and Loki and gain power over Asgard. Since she's a new and potentially vulnerable target, he could try to use her in his dark schemes.

Perhaps a group of inter - dimensional bounty hunters. They've heard about Loki's children and the potential power they might possess when they grow up. So they target the children to either sell them to the highest bidder or use their powers for their own evil purposes. Tony then has to fight against this group to save the kids.

One possible scenario in this fanfiction could be that Loki disguises himself and lures Spiderman into a trap. He then transports him to a different realm where Spiderman is completely out of his element. Spiderman would have to rely on his wits and basic powers to try and escape Loki's clutches.

Another plot twist could be that the reader has some sort of power or knowledge that Loki needs. So, instead of a malicious kidnapping, it's more of a strategic move on Loki's part. He might be trying to bargain with the reader to get what he wants, but as time passes, he starts to develop feelings for the reader.

One possible plot twist could be that Loki actually has a noble reason for kidnapping Tony. Maybe he wants to use Tony's intelligence to stop a greater threat that the other Avengers are unaware of. For example, there could be a hidden enemy that Loki has knowledge about, and he believes only Tony can help create a device or strategy to defeat it.

One possible plot could be that Loki kidnaps Natasha to use her as a bargaining chip against the Avengers. He might think that her skills and the Avengers' attachment to her would make them more likely to give in to his demands.

One main character could be a young scientist. This person could be intrigued by Loki's arrival and his other - worldly powers. They might try to study him in a non - invasive way, which could lead to some interesting interactions between them. Another character could be a street - smart kid who Loki befriends. The kid shows Loki the ropes of the city and in return, Loki protects the kid from the local bullies.