Percy himself, of course. Given his leadership skills and powerful abilities, he would be the first to step up and face the Pillar Men. His ability to control water could be a great asset or a hindrance depending on the situation.
Grover might also be involved. His ability to sense emotions and his connection to nature could play a role. He could be the one to initially sense Padme's arrival or help her understand the more magical and nature - related aspects of the Percy Jackson world, like the power of the gods and the spirits of the forest.
Draco Malfoy would be a likely character. Given his Slytherin status, he would likely have a complex relationship with Percy. He might start off as hostile, seeing Percy as an outsider, but then they could end up having to work together for some reason.
Issei would be really interesting. He's the main character in DxD and has his own set of powers and a rather unique personality. His pervy nature would contrast with Percy's more heroic and sometimes serious demeanor. Their interactions could be both comical and lead to some great character development for both.
Sasuke and Magneto. Both are complex characters with a bit of a dark side. They could either become enemies as their goals might clash. Sasuke is on a journey to gain power for revenge, and Magneto wants to protect mutants but sometimes uses extreme methods. Or they could form an unlikely alliance, learning from each other's determination and power - seeking motives.
Well, Annabeth would definitely be one. She's always been by Percy's side, and in this fanfiction, she might be a bit worried about Percy being the champion of Nyx. She could be trying to help him while also being cautious of Nyx's motives.
Naruto himself is often a popular choice to be paired with the Pillar Men. His positive attitude and strong will make for an interesting contrast and potential for character growth when interacting with the more menacing Pillar Men. Another popular character is Sasuke. His brooding nature and powerful abilities can create some intense storylines when combined with the Pillar Men.
Probably Wolverine and Spiderman. Wolverine is often on the front lines in X - Men stories, and his no - nonsense attitude would contrast well with Spiderman's quippy nature. They might meet when investigating a strange occurrence in New York that involves both mutants and non - mutants.
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.
Death from DarkSiders and Black Widow could have an interesting interaction. Death has seen countless deaths and has a very different perspective on life and death compared to the human Black Widow. Their conversations could be deep and thought - provoking as they work together on a mission.
I think Mirabel from Encanto and Aang from Avatar would be likely to interact. Mirabel is all about finding her place in the family and Aang is on a journey to save the world. They could share their experiences of feeling different and having big responsibilities.