It could also be that the kidnapper is under the control of some dark force. For example, a powerful evil entity might want to corrupt Nico or use his powers for its own evil purposes. In some fanfictions, the motive might be related to a prophecy where Nico's presence or absence is crucial for some major event.
Well, one possible motive could be that the kidnapper is a villain who wants to use Nico as a bargaining chip against the other demigods. Maybe they want to trade him for some powerful artifact or to gain access to the Underworld. Another motive could be that the kidnapper has a personal vendetta against Nico or his family.
Well, it could be about Nico Di Angelo using his underworld powers to help the Avengers in a battle against a powerful villain who has the ability to raise the dead. Maybe he teams up with Doctor Strange to close portals to the underworld that the villain is using to summon hordes of zombies.
A third plotline could be a more comical one. Nico, being from a different world of demigods, might not understand all the wizarding world's customs. His interactions with Umbridge could lead to some really awkward and funny situations. For example, he might accidentally use his powers in front of her in a way that completely baffles her, or he might misunderstand some of her rules and break them in the most unexpected ways.
The group as a whole would be very worried about Nico's well - being. They would put aside any differences they might have had and work together. They'd also be worried about what the kidnapper might be doing to Nico. They might fear that he's being tortured or used for some evil plan. So they would be in a hurry to rescue him before any real harm comes to him.
One possible theme could be friendship. Maybe his friends are tickling him as a form of play or to cheer him up. Another theme might be vulnerability. Since tickling can make a person seem more vulnerable, it could show a different side of Nico di Angelo.
In a fanfiction where Nico di Angelo meets Dumbledore, there are numerous possibilities. Nico might be initially distrustful of Dumbledore, given his own experiences with authority figures. However, Dumbledore's calm and kind demeanor could gradually break down Nico's walls. Dumbledore could introduce Nico to the wonders of the wizarding world, such as spells and magical artifacts. Nico, in turn, could show Dumbledore some of his demigod abilities, like shadow - traveling. Their meeting could also lead to a cultural exchange of sorts, with Nico learning about Hogwarts and Dumbledore getting a peek into the life of a demigod.
In such a fanfiction, there could be an epic battle. Nico's powers from the Percy Jackson universe might clash with the Winchesters' hunting skills. Maybe they initially misunderstand each other, thinking the other is a threat. But then they could realize they are all fighting against some form of evil and team up. For example, Nico could use his ability to control the dead to help the Winchesters deal with a horde of zombies, while the Winchesters could teach Nico some of their combat tactics against demons.
One possible plot could be that Nico somehow gets transported to the Harry Potter world. He might use his powers from the Percy Jackson universe, like shadow - traveling, to his advantage in the new magical world. Maybe he helps Harry and his friends in their fight against Voldemort by providing unique strategies based on his own experiences with battles in his own world.
One possibility is that Nico, with his powers over the dead, could really freak out Batman at first. Batman is used to dealing with normal criminals and the occasional super - villain with scientific powers. Nico's dark and otherworldly abilities would be something completely new to him. Maybe Nico would mistake Batman for some sort of undead creature at first because of his all - black costume and brooding nature.
Perhaps in the fanfiction, Nico gets the puppy as a gift from a mysterious figure. The puppy is a special breed that is only known in the demigod world. Nico has to learn how to take care of this unique puppy. He has to figure out what it eats, how to train it, and also how to protect it from the various dangers that lurk in his world.
In the fanfiction, Nico might find himself in some of the Marauders' pranks. Since the Marauders are known for their mischief, they could include Nico in one of their elaborate schemes against the Slytherins. Nico, being from a different background, might have a different perspective on these pranks and could either enhance them or try to stop them depending on his moral compass at that moment.