In the Injustice 2 Batman ending story, Batman manages to defeat Superman. He restores order to a world that has been torn apart by the chaos of the Injustice regime. With Superman out of the way, Batman is able to start rebuilding society, bringing back justice and the rule of law. He also has to deal with the remaining super - villains and ensure that they are locked away safely.
Well, in the Injustice 2 Batman ending story, Batman finally prevails. He has been through a lot in the fight against Superman and his regime. After his victory, he focuses on mending the broken world. He works on reuniting the fractured Justice League, or at least what's left of it. Batman uses his skills and intellect to reverse the damage done to society. He has to re - establish trust among the people, who have been living in fear for a long time. He also has to figure out how to handle all the super - powered individuals in a way that doesn't lead to more destruction. It's a long and arduous process, but Batman is up to the task.
The key event is Batman defeating Superman. Then he begins to restore order in the world.
It depends on personal preferences. Some might like the heroic ending, while others might find the darker one more compelling.
The canon ending of Injustice 2 is often determined by the game's storyline and the decisions made by the developers to shape the overall narrative. Usually, it's the one that ties in with future installments or related media.
Perhaps a story where Batman discovers a conspiracy within the Injustice League that involves mind - controlling the heroes. It could delve into his detective skills as he tries to uncover the truth and save his comrades. This would be full of mystery and action.
One idea could be exploring Batman's internal struggle in the Injustice universe more deeply. Maybe he has a nightmare where he becomes like the tyrannical Superman, and this makes him question his own actions and methods even more.
Nightwing is a great choice. He has a strong connection to Batman as his former sidekick. In an Injustice fanfiction, Nightwing could be the voice of reason when Batman starts to go too far in his fight against Superman. Their relationship, with all its history and baggage, can add a lot of depth to the story.
Batman used his strategic mind and some special gadgets to outsmart and stop The Flash. It was a combination of planning and unexpected tactics.
One idea could be that Batman tries to train Supergirl to better control her powers in the context of the Injustice 2 universe. He might see her as a potential force for good against the tyrannical regime. Another could be that Supergirl discovers a way to bring back the more heroic Superman she once knew, and Batman has to decide whether to trust her plan or not.
One interesting storyline could be a redemption arc for Superman. In the Injustice universe, Superman has gone down a dark path. A fanfiction might explore how Batman tries to bring back the good in him, with lots of emotional confrontations and moral debates between the two.
One idea could be exploring an alternate universe where Terry McGinnis (Batman Beyond) is pulled into the Injustice universe and has to deal with the morally compromised heroes. He might try to find a way to bring back the true sense of justice among them. For example, he could start by trying to reason with Superman, showing him the error of his ways through his own experiences in his own universe.