Another unlikely pair could be Percy and Hulk. Hulk is all about brute force and anger - driven power. Percy is more in tune with his strategic thinking as a demigod. But if they were in a situation where they had to fight a huge, powerful enemy, like a giant from Greek mythology that has been enhanced by some sort of modern technology, Percy could use his water to cool Hulk down when he gets too angry and Hulk could use his strength to physically take on the enemy. Together, they could be a surprisingly effective team.
I think Loki and Crowley would be quite the unlikely allies. Loki is known for his trickery and self - serving nature in the Avengers universe, and Crowley from Good Omens is also a demon who loves to cause a bit of chaos. They could team up to play pranks on both the Avengers and the forces of Heaven and Hell from Good Omens. Maybe they'd create illusions to mislead everyone and have a good laugh while doing it.
I think Luke Skywalker and Olaf would be quite an unlikely pair. Luke is this serious Jedi Knight, trained in the ways of the Force, while Olaf is a carefree, snowman who loves warm hugs. But perhaps Olaf's innocence and positive attitude could teach Luke to not be so burdened by the weight of the galaxy all the time.
Definitely Loki. In a 'Percy Jackson and Avengers crossover fanfiction', Loki would find Percy's world of Greek gods and demigods fascinating. He could try to use Percy's knowledge of the gods to his own advantage, or maybe even form an unlikely alliance with Percy. Loki's mischievous nature would add a whole new layer of chaos and intrigue to the crossover.
It's hard to say. Thor has his godly powers and Mjolnir. But Percy can control water and has defeated many powerful monsters. It could be either depending on the situation.
Bellatrix Lestrange and Nightwing would be an unexpected duo. Bellatrix is a deranged Death Eater, and Nightwing is a symbol of good in Gotham. But if Voldemort made a deal with a Gotham super - villain to take over both worlds, and Bellatrix was sent to work with Nightwing as part of the deal, they would have to find a way to coexist, at least temporarily. Their interactions would be full of tension and power struggles.
I think the interaction between Hulk and Grover would be fascinating. Grover is this gentle, nature - loving satyr, and Hulk is, well, the big green rage - monster. Grover could try to use his empathy and nature powers to soothe the Hulk, which could lead to some really comical and heartwarming moments. Also, Natasha Romanoff and Clarisse would be an interesting duo. Natasha's stealth and combat skills combined with Clarisse's brute force and no - nonsense attitude could make for some great fight scenes and character development.
I think Klaus and Loki could be likely allies. They both have a sense of mischief and are often underestimated. They might team up to outwit their more 'righteous' counterparts. Klaus has his vampire powers and Loki has his Asgardian magic and trickery.
Inuyasha and Thor could potentially be allies. They both have a sense of honor and are very powerful warriors. Thor with his hammer and Inuyasha with his sword could fight side by side against powerful enemies. Also, Captain America and Inuyasha might get along. Captain America would respect Inuyasha's fighting skills and determination, and Inuyasha would see Captain America as a worthy leader.
Well, one way their worlds could collide is through a common enemy. Maybe some ancient Greek monster has found a way into the modern world of the Avengers. Percy, with his water - controlling powers and combat skills, could team up with Thor, who also has power over a natural element. They would make a formidable duo against this threat.
I think Percy Jackson and Thor would make an interesting pairing. Percy has his connection to water and the sea, while Thor is associated with lightning and thunder. They both have a sense of heroism and loyalty. Percy could learn about different forms of power from Thor, and Thor could be intrigued by Percy's ability to control water in such a unique way. They might also have some friendly competitions, like who can control their element better in a given situation.