Perhaps a plot where Tony, in his quest for knowledge, accidentally stumbles upon an ancient Asgardian spell. This spell starts to have strange effects on him and his technology. Thor, being familiar with Asgardian magic, comes to help. Together they have to figure out how to reverse the spell's effects before it causes chaos. Along the way, they encounter various challenges like dealing with other Asgardians who are not happy that a Midgardian is meddling with their magic, and also Tony's own hubris getting in the way of a solution.
A cool plot could be that Thor and Tony have a bit of a rivalry at first. Thor thinks Tony is too full of himself with his high - tech gadgets, and Tony thinks Thor is just a brute with a hammer. But then they are forced to work together when an alien threat arrives that is immune to Tony's tech and Thor's brute force alone. As they get to know each other better, they learn to combine their strengths and defeat the enemy. They might even become good friends in the end.
A possible plot could be that Thor discovers Tony's love for food and tries to court him through cooking Asgardian delicacies for him. Since Tony is always busy in his lab, Thor could also offer to help him with his projects in his own Thor - like way, which might initially cause some chaos but eventually lead to them getting closer. Or perhaps Thor and Tony are forced to go on a mission together where they are stranded in a strange place. In this difficult situation, they rely on each other and Thor starts to court Tony more seriously.
One idea could be exploring Jane's further adventures on Earth while Thor is away in Asgard. Maybe she discovers some new scientific phenomena related to the Aether that was in her. Another could be Thor taking Jane to a secret part of Asgard that no human has ever seen before, and they face some challenges there together. Also, a plot where Jane gets kidnapped by an enemy of Thor's and Thor has to rescue her, but during the rescue he discovers some new powers within himself.
One interesting Thor and Tony fanfiction could be a story where they team up to fight a new, powerful villain that neither of them could defeat alone. They start off bickering due to their different personalities but gradually learn to work together and respect each other's strengths.
One idea could be that Tony tries to use his technology to control Surtar's power for some noble purpose, like saving a world from a different threat. But he quickly realizes it's a much more dangerous task than he thought.
Another plot could be that Tony creates a device that can transfer intelligence. He accidentally transfers some of his own intelligence into Hulk. This causes Hulk to become more intelligent and he starts to question his own existence and role in the world. Together, they embark on a journey to find a way to reverse the process while also learning a great deal about each other.
A possible plot could be that Surtur has a part of his essence trapped in a piece of Asgardian relic on Earth. Tony discovers this relic and when he touches it, he starts having visions of Surtur. Surtur then starts to communicate with Tony through these visions, asking for his help to be fully reborn. Tony is hesitant but realizes that if Surtur is reborn in the wrong way, it could mean the end of the world. So he decides to work with Surtur, but on his own terms. This could lead to a lot of interesting interactions between the two as they have very different personalities and goals.
A plot could revolve around slutty tony's attempt to revive an old - fashioned fashion house. He has to deal with the traditionalists who are against his modern and flamboyant ideas. He uses his unique charm and out - of - the - box thinking to bring new life to the brand, while also facing some personal scandals that threaten to derail his efforts.
They could be in a post - apocalyptic world. Jessie has some special skills like being able to find water sources and Tony is good at building shelters. Together, they try to survive and build a new community, facing many challenges along the way like fighting off raiders and dealing with scarce resources.
One plot idea could be that Hermione, through some magical accident, ends up in the Asgardian realm. Thor then has to help her get back home while she uses her magic to solve various problems in Asgard, like dealing with a mysterious magical threat that the Asgardians' magic can't handle.
One plot idea could be Thor landing in the Viking era and being mistaken for a god. The Vikings might try to either worship or challenge him. Another could be a Viking warrior being chosen by Thor to help him on a quest in Asgard. Or perhaps Thor has to team up with a group of Vikings to fight a common enemy like a giant frost monster.