There probably is. Given the popularity of both Darkseid and Batman in the DC universe, it's a common and rather dark theme for fanfiction writers to explore. Some might write it to show the extreme power of Darkseid, while others may use it as a starting point for a more complex alternate universe story where Batman's death has far - reaching consequences for other characters.
One of the best is 'Final Crisis'. In this story, Darkseid's plan to reshape reality is opposed by Superman. It shows Superman's unwavering will against Darkseid's tyranny. Another great one is 'Superman: The Darkseid War'. It features an epic battle between them with high - stakes and amazing power displays.
One possible plotline could be that Darkseid is about to destroy Gotham or Earth in a way that Batman has no other option but to kill him. Maybe all of Batman's usual gadgets and allies are useless, and he has to use a kryptonite - like weapon (if it could affect Darkseid) to take him down.
A 'Darkseid Kills Batman' fanfiction could center around the build - up to Batman's death. It might show Batman's attempts to outwit Darkseid but ultimately failing. Then, it could explore the aftermath, such as how Gotham descends into chaos without its protector, and how the Justice League is affected. There could also be a sub - plot about a character seeking revenge for Batman's death.
It's a somewhat unique concept. In the mainstream DC universe, Darkseid is an extremely powerful villain. For Batman to kill him in fanfiction goes against the norm where Batman usually uses his wits and non - lethal means. It shows the creativity of fanfic writers who want to explore extreme scenarios and different power dynamics.
Definitely 'Final Crisis'. It's super popular. It's a huge, multi - faceted story where Superman's battle against Darkseid is central to the plot. There are so many heroes involved, and the scale of the conflict is massive.
Yes, there are likely some out there in the vast world of fanfiction. Fanfiction writers often come up with unique and unexpected crossovers like this. However, the quality and popularity can vary greatly.
Yes, there are some out there. You can start by looking on popular fanfiction websites like Archive of Our Own or FanFiction.net. Just search for the specific tag'superman kills batman' and you'll find a variety of stories. However, the quality can vary greatly from one to another.
One possible reason could be mind control. Maybe some villain has taken over Superman's mind and made him do it. Another reason might be a fundamental difference in their ideologies that has escalated to the point of no return.