Well, Percy's ability to control water and Frozen characters' ice powers could create some cool interactions. For example, Percy could make a stream of water and Elsa could freeze it to create an ice bridge. It would be a great way for them to traverse difficult terrains.
The vampires' super strength and speed in Twilight could be a match for the physical abilities of some of the stronger demigods in Percy Jackson. For example, Emmett's brute strength might be on par with that of a son of Ares. However, the demigods have their own unique powers. Percy's control over water could be a huge advantage. He could create water barriers to keep the vampires at bay, as vampires are not that great with water.
Annabeth, if she were with Percy, would be more interested in the architecture and strategic planning of Troy. She could offer her knowledge to the Trojans or the Greeks, but they might not trust her either. And Percy would have to protect her from those who might see her as a threat or a sorceress.
Percy would probably be very cautious around Morathi at first. Given his experiences with tricky and powerful beings, he'd be on guard. Morathi, being the conniving character she is, might try to charm Percy or manipulate him. For example, she could use her allure to make Percy lower his defenses, but Percy's loyalty to his friends and his own sense of right and wrong would likely make him resist.
The two could have some really interesting conversations. Percy could talk about his adventures with Annabeth and the other demigods, while Jacob could share stories about his pack and his experiences in the forest. They might also compare their different kinds of powers. Percy's control over water and his ability to withstand a lot of physical damage compared to Jacob's enhanced senses and super - strength as a werewolf. And they could learn from each other. Percy could teach Jacob some Greek, and Jacob could show Percy how to track better in the wild.
Percy would likely be initially cautious yet intrigued by Rory. He might be in awe of her combat skills and the way she commands in battle. Rory, on the other hand, would be curious about Percy's powers related to the sea and his connection to the Greek gods. They would probably start by exchanging stories about their respective worlds and gradually build a bond based on mutual respect and the need to face common threats.
Percy would probably be initially cautious when interacting with Egyptian gods. For example, when meeting Ra, the sun god, Percy might be in awe but also a bit hesitant as their powers are so different. He would need to show respect as he does with the Greek gods. The Egyptian gods, in turn, might be curious about Percy's abilities, especially his control over water which is not as prominent in Egyptian mythology.
In a fanfiction, the characters' personalities would greatly influence their interactions. Percy is a bit of a rebel and a free spirit, which could either clash or mesh well with the more structured Avengers. Thor, being a god - like figure in his own right, might recognize the power and divinity within Percy and the other demigods. They could share stories about their respective mythologies. Natasha Romanoff could take an interest in the demigods' combat training, which is different from her own. She might learn some new fighting techniques from them, while also teaching them some of her stealth and espionage skills.
At first, they might be cautious around each other. Aquaman, being the king of Atlantis, would be wary of this strange demigod from the surface world. Percy, on the other hand, would be in awe of Aquaman's power and the strange underwater world. But as they face challenges together, like fighting off some menacing sea creatures or stopping a villain who wants to control the ocean, they would start to respect and rely on each other. Percy might crack some jokes to lighten the mood, which Aquaman might find strange at first but then start to appreciate as a sign of Percy's courage.
Hulk and Percy could have an interesting interaction. Hulk's brute strength and Percy's agility and water powers could make for a great dynamic. They might start off by having a little test of strength, but then realize they need to work together. And when it comes to Captain America, he and Percy could bond over their sense of duty and loyalty. Cap would probably respect Percy's commitment to protecting his world, just as Percy would admire Cap's leadership.
The demigods from Percy Jackson's world would interact with the Diablo characters in different ways depending on their personalities. Annabeth, being the strategic thinker, would try to analyze the Diablo characters' weaknesses and form plans. She might try to communicate with any intelligent Diablo creatures to find out more about their world. Grover, with his connection to nature, might be really disturbed by the corrupted and dark nature of the Diablo world. He could try to find any remnants of good or nature in that world to help in the fight against the dark forces. And when it comes to the Diablo characters, some of the more cunning ones might try to manipulate the demigods for their own ends.