At first, Percy would be in shock. He'd be taken from his familiar world of demigods and suddenly be in this strange place with Dumbledore. But then his survival instincts would kick in. He'd start looking for weaknesses in his captor and the environment. He might try to reason with Dumbledore at first, but if that doesn't work, he'd resort to using his powers. He'd also be constantly thinking about how to get back to his friends and family at Camp Half - Blood, and he'd be worried about what threats they might be facing without him.
Percy would first be confused. He doesn't know Dumbledore or the wizarding world. Then he'd likely become defiant. He has a strong sense of loyalty to his friends and his own world, so he'd want to escape and get back. He might also be a bit curious about the new magic around him, but his main goal would be to get free.
Percy would be really angry. He's used to being in control of his own situation, and being kidnapped is not something he would take lightly. He'd probably try to fight back right away, using his demigod powers like his sword fighting skills and his ability to control water.
Well, in a fanfiction scenario, if Dumbledore kidnapped Percy Jackson, it could lead to a really strange and interesting mix of the two universes. Dumbledore might be interested in Percy's powers, especially his connection to the water and his demigod abilities. Maybe he wants to protect Percy from the threats in Percy's world by taking him to Hogwarts. But Percy would surely be confused and probably try to escape to get back to his friends and his own world.
The Ministry of Magic would probably be in an uproar. They might see Dumbledore's actions as a blatant abuse of power. They would send out Aurors to search for Harry and arrest Dumbledore. After all, Dumbledore is one of the most powerful wizards, and his actions would be seen as a threat to the stability of the wizarding world.
The gods might also get involved. Zeus, for example, would not be happy that a human organization had kidnapped one of his son's (Poseidon's) demigod children. He might send some signs or even directly interfere. Athena would be giving Annabeth advice on how to deal with SHIELD. And Poseidon himself might stir up the seas near SHIELD facilities to show his displeasure.
Percy would probably be very confused at first. He's used to dealing with threats from the world of Greek mythology, not superheroes like the Avengers. But once he realizes he's been kidnapped, he'd likely be angry. He'd try to find a way to escape using his powers, like controlling water to create distractions or even using it to overpower his captors.
His first reaction might be shock. Dragons aren't exactly common in his world, even with all the mythical creatures. But then his hero instincts would kick in. He could try to befriend the dragon, thinking it could be an ally in future battles against the Titans or other enemies. He might offer it some food, like a fish or something, to gain its trust.
Percy's reaction would be complex. On one hand, he would respect the Avengers' powers. He'd see Iron Man's intelligence - based powers as a different kind of 'gift' compared to his own demigod abilities. He might be a bit intimidated by the combined might of the Avengers at first. But then, he would start to analyze their powers. He would think about how Captain America's leadership and physical abilities are like the qualities of some of the heroes in his own world. And he'd be constantly comparing and contrasting their powers with his own and those of his friends, trying to find common ground or new ideas that could help him in his own adventures.
Percy would be angry. He has been through a lot in his own world and being betrayed again would not sit well. He'd probably lash out with his powers at first.
Well, some past gods might be amused. They'd see these modern interpretations of their stories and characters in the Percy Jackson fanfiction as a strange yet interesting new form of worship or at least attention. For example, Zeus might be a bit irked at some of the liberties taken with his character, but also secretly flattered that people are still so interested in him.
Ruby would be excited. She loves stories full of action and adventure, and Percy Jackson fanfiction would be right up her alley. Weiss might be a bit more reserved, but could still find aspects of it to enjoy, like the complex characters. Blake would be interested in the themes of the story, such as loyalty and friendship. Yang would be enthusiastic, especially about the fight scenes and the strong characters in the fanfiction.
Percy would probably be both terrified and intrigued. He's used to facing powerful monsters, but Cthulhu is on a whole different level. He might initially try to attack Cthulhu out of instinct, but quickly realize that his usual weapons and powers might not be enough. So he would likely retreat and try to come up with a more strategic plan.