Thor could also be a troublemaker. He's from Asgard and might not be familiar with Earth's shopping etiquette. He could end up using his hammer in inappropriate ways, like trying to smash open a locked display case to see an item better.
Hulk. He has a tendency to lose control and his large size could easily knock over shelves or accidentally break items.
Black Widow. She has a lot in common with Batman in terms of skills. Both are highly trained in combat, stealth, and espionage. They would understand each other's need for secrecy and their ability to operate in the shadows.
Thanos could still be a likely villain. Even if he was defeated in the official storyline, in a fanfic he could return more powerful or with a new plan. His obsession with the Infinity Stones makes him a great overarching threat.
I think Iron Man and the Flash would get along well. Iron Man is always interested in new technology and the Flash's super - speed abilities are like a form of amazing technology. They could have long discussions about how the Flash's powers work and Iron Man might even try to create something inspired by it.
Loki could be the one most likely to start a conflict. He's always been a bit of a troublemaker in the Avengers world. In a meeting with Percy Jackson and his group, Loki might see an opportunity to cause chaos. He could try to manipulate the situation by pitting the Avengers against Percy and his friends, thinking he can use the confusion to his advantage.
Captain America is very likely to be featured. He has that paternal, moral - compass kind of vibe. He would be the one to gently tickle the 'daughter' as a way of showing his soft side. Thor could also be a popular choice. His big - hearted and sometimes child - like nature would make for some great tickle - related antics with the 'daughter' figure.
Thor would be one of the active ones. He has a lot to share from his Asgardian experiences. Hulk, well, he might not type much but when he does, it would be in short, powerful statements. And Scarlet Witch could be in there too. She could use her powers to sense if there's any danger approaching the chatroom or the Avengers themselves while chatting with the others.
Magnus Bane and Doctor Strange would make a great pairing. They are both powerful magic - users. Magnus could introduce Doctor Strange to the magic of the Shadow World, and Doctor Strange could share his knowledge of the mystic arts from the Marvel Universe. They could collaborate on spells and magical defenses against common enemies.
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.
Iron Man. They both are very intelligent and rely on their technology a great deal. They could share ideas about improving their gadgets and suits.
Iron Man and Batman might be the most likely to clash. Iron Man is all about high - tech and showing off his latest inventions. Batman, while also using technology, is more of a brooding, solitary figure. Iron Man might see Batman as a bit of a relic or too old - fashioned in his methods. Batman, in turn, could view Iron Man as a bit too flashy and irresponsible with his power. Their egos could get in the way of them working together initially.