Well, in some fanfictions, there might be a plot twist where the portals between the different Earths malfunction in a new way. Instead of just allowing the heroes and villains to cross over, they start merging certain parts of the different Earths. So you might have a city on Earth - 1 that suddenly has a section that looks like it's from Earth - X. This would create all sorts of chaos and new challenges for the characters to deal with. It also gives an opportunity for different versions of the characters to interact in unexpected ways, like a more peaceful version of a villain from one Earth having to face off against their more malevolent counterpart from another Earth that has now invaded their space.
A great plot twist in Crisis on Earth X fanfiction could be the revelation of a hidden alliance. Maybe there's a group of characters from different Earths that have secretly been working together all along. For example, some minor characters from Earth - 2 and Earth - 3 who have been pulling the strings behind the scenes. This could lead to a big showdown where the main heroes thought they knew who their enemies were, but now they have to face this new threat that has been manipulating events from the shadows.
A possible plot is centered around the relationships that form during the crossover. Imagine a love story between two characters from different Earths. Maybe a hero from Earth X falls in love with a hero from the main Earth. This relationship could be complicated by the differences in their worlds and the events of the Crisis. Also, a plot about the heroes having to adapt to the different rules and cultures of Earth X would be engaging.
One interesting concept could be exploring alternate versions of characters that we didn't see in the original 'The Flash Crisis on Earth X'. For example, what if there was a version of Barry Allen with different powers or a different moral code? Another concept could be delving deeper into the relationships between characters from different Earths. Maybe a fanfiction could focus on the friendship or rivalry between characters that only briefly interacted in the actual storyline.
One aspect to consider in 'Crisis on Earth X' fanfiction could be the exploration of alternate versions of characters. Writers often take advantage of the multiverse concept in this storyline to create unique character arcs that deviate from the original canon.
Fanfiction often gives the opportunity to develop secondary characters more. In the context of Crisis on Earth X, these characters can play crucial roles. They might have unique skills or knowledge that help in dealing with the crisis, and their growth and contribution can be a central part of the fanfiction story.
One idea could be a crossover of characters from different Arrowverse shows on Earth X. For example, having Barry Allen from 'The Flash' team up with Kara Danvers from 'Supergirl' to fight against the evil regime on Earth X. They could use their super - speed and super - strength respectively to take on the powerful foes there.
One possible plot twist could be that on Earth 39, Alex has some latent superpower that she discovers. This would completely change the dynamic between her and Kara, as now they both have super - abilities. Another twist could be that the version of Kara on Earth 39 is actually an evil doppelganger, and the real Kara has to convince Alex that she is the true one.
How about a plot twist where Garou suddenly loses his powers. Metal Bat, who has always seen Garou as a powerful adversary, now has to protect him. This forces them to work together in a new way and also makes Metal Bat re - evaluate his perception of Garou.
A plot twist could be that the wolf is actually a cursed prince. When he blows on the pigs' houses, it's because he's trying to break the curse by performing a certain task. The pigs find out about this and instead of fighting him, they help him break the curse. In return, the prince (formerly the wolf) rewards them handsomely.
In some fanfics, like 'The Unexpected Ally', a plot twist could be that Venom actually has a hidden connection to Peter's family history. This completely changes the dynamic between them as they start to uncover secrets together.
Well, a plot twist could be that the girl is actually from a different time in Middle Earth's history than she thought. Maybe she was sent there not by accident but as part of a prophecy that no one in Middle Earth knew about. This could lead to her having to convince the different races, like the dwarves and hobbits, that she is there for a purpose. Also, she might be the only one who can enter a certain enchanted place because of her unique origin, and inside that place lies the secret to stopping the dark forces.