A possible plot idea is that Thor, as a yandere, believes that only he truly understands Loki. So he starts to manipulate situations to make Loki seem like the bad guy to others, so that Loki has no one else to turn to but him. For instance, he could frame Loki for minor misdeeds in Asgard. Another plot could be that Thor's yandere nature is triggered by a prophecy that Loki will leave him one day. So he goes to extreme lengths to keep Loki by his side, even if it means changing Loki's very nature or imprisoning him in a gilded cage of sorts.
Well, a plot could involve Thor being secretly in love with Loki in a yandere way. He might start to interfere with Loki's relationships, for example, scaring off any potential friends or allies Loki has. Or perhaps there's a threat to Asgard, and Thor's yandere tendencies towards Loki make him prioritize Loki's safety over the whole of Asgard. Also, Loki could notice Thor's strange behavior and try to figure out what's going on, leading to a tense and interesting dynamic between them.
One plot idea could be Thor becoming overly possessive of Loki after Loki gets too much attention from other Asgardians. Thor starts to isolate Loki, thinking it's for his own good. Another could be in a situation where Loki is injured, and Thor's yandere side emerges as he refuses to let anyone but himself tend to Loki. A third idea is that Thor, in his yandere state, tries to make Loki dependent on him by controlling all aspects of Loki's life in the name of protecting him.
One idea could be Loki, in his Jotun form, is initially feared by Thor but then Thor realizes that beneath the different appearance, Loki is still the same person he cares about. They could go on a quest together where Thor has to protect Loki from Asgardians who don't trust the Jotun form.
One plot idea could be Thor and Loki as younglings getting into mischief in Asgard's forbidden areas. Maybe they accidentally unleash a minor magical creature that causes chaos in the palace. Another could be a story where they compete in a friendly, yet intense, training tournament to prove who is the better warrior at a young age. And they could also go on a secret adventure outside of Asgard, defying Odin's rules, to explore a rumored enchanted forest.
Their relationship can be developed by showing Thor's gradual descent into yandere behavior. At first, it could start with small acts of overprotectiveness, like Thor always being by Loki's side during battles. Then, as time passes, it becomes more extreme. Loki, on the other hand, can initially be confused by Thor's actions, but then slowly realize the depth of Thor's obsession. This realization can lead to different reactions from Loki, either trying to escape or, in a more complex scenario, starting to have some strange, Stockholm - like feelings for Thor.
One plot idea could be that Baby Loki gets into some sort of magical mischief in Asgard while Thor tries to keep him out of trouble. For example, Loki might accidentally turn all the flowers in the palace gardens into snakes, and Thor has to figure out how to reverse it before the other Asgardians find out.
A plot idea might be that Sasuke, in his yandere state, secretly follows Naruto everywhere. He then starts to eliminate any potential danger to Naruto, even if Naruto doesn't see it as danger. For example, if a merchant is a bit rude to Naruto, Sasuke might find a way to drive the merchant out of the village. Also, Sasuke could be very controlling about Naruto's missions, trying to ensure that he's always by Naruto's side during them.
One plot idea could be that Kise, in his yandere state, becomes overly possessive of Kuroko. He might try to isolate Kuroko from his other friends, like the Generation of Miracles. For example, he could spread false rumors about them to make Kuroko distance himself. Another idea is that Kise secretly follows Kuroko everywhere, taking pictures of him without his knowledge and creating a sort of 'private collection' which he treasures dearly. It could also be a story where Kise's yandere tendencies are triggered by another character showing too much interest in Kuroko, leading to a conflict between his love and his dark side.
A plot could revolve around Makoto being aware of Junko's yandere tendencies but trying to reform her. He constantly battles her dark desires and possessiveness with his own belief in the good of people. This creates a constant tug - of - war between them, with Junko's love for Makoto becoming more and more warped as she tries to keep him to herself against his will.
Well, a possible plot could be set in an alternate universe where Kaguya is resurrected as a yandere. She sees Naruto as the key to her new world order and her yandere love makes her go to extreme lengths to get him on her side. Maybe she uses her powers to create illusions that only Naruto can see, trying to manipulate his perception of reality and draw him closer to her.
Well, a plot could be Loki disguising himself as a Hogwarts student. He gets involved in the house rivalries and eventually meets Harry. They start off as adversaries but then realize they both have a common goal of protecting the wizarding world from a hidden danger. For example, an ancient evil that is about to be awakened. Loki could use his Asgardian knowledge and Harry his wizard skills to defeat it. Also, Loki could be interested in the magic of the wizarding world and want to learn more, leading to some humorous and interesting interactions with the Hogwarts professors.
One idea could be a story where Loki and Black Widow are forced to team up on a mission in a parallel universe. They have to overcome their initial distrust of each other due to their different backgrounds and allegiances.