I'm not sure specifically as there could be many interpretations of such a fanfic. It might involve a scenario where Guts, a character, kills Griffith in a fictional story created by fans. Maybe it's about Guts seeking revenge on Griffith for some past wrongs in the context of the original story's lore.
Perhaps in this fanfic, Griffith has turned into something truly evil and a threat to the world Guts cares about. Guts, being the warrior he is, might feel it's his duty to put an end to Griffith to save others. Also, Guts could be driven by his own sense of justice. If Griffith has wronged innocent people, Guts may decide that killing him is the only way to set things right.
It depends on the specific fanfic. Some fanfics might have Guts killing Griffith as a major plot point, while others could take a different direction and not have that happen at all.
Finding fanfics can be a bit tricky. You could start by searching on popular fanfic websites like Archive of Our Own (AO3) or FanFiction.net. Just type in 'guts kills griffith' in the search bar and see if it comes up.
We can come to the following conclusion: The Legend of the Apostles is a web novel written by Moran. This novel contained many chapters, including chapters 160, 150, 56, 76, 19, and 159. However, these search results did not provide any information about the specific content or storyline of the Legend of the Apostles. Therefore, we have no way of knowing the details of the Legend of the Apostles.
The names of the apostles in the Eva were as follows:
1 Adam
2 Lilith
3 Eve (Eve)
4 Apostle (Eve)
5. Eufemia
6 Sebastian
7 Karl
8. Lilith Sabot (Lilith Area: 06m2)
9 Cyrus (Willow)
Yuna (Yun)
11 Sebastian Michaeli
12 Cyrus Springston (Willowston)
13 Isis
14 Lana
15 Albert
16 Lilith Lei
Cyrus Monterey (Willow Monterey)
18 Adam Malcolm
19 Lilith Kille
20 Albert Monterey
21 Yuna Monterey
22 Adam Johnson
Cyrus Cassel (Willow Karsel)
24 Isis Karsel
25 Lilith Press
Cyrus Sabot (Willow Sabot)
27 Adam Sabot
Cyrus Monterey (Willow Monterey)
29 Yuna Monterey
30 Cyrus Preston (Willow Preston)
Guts is purely fictional. It's a concept or character that exists within the realm of imagination and creative storytelling rather than being based on reality.
The Infinite Apostle and the Twelve Battle Maidens were an anime. It described that among the twelve apostles at the top of the world, Ullman was publicly recognized as the strongest existence. He was a character that was difficult for humans to understand because no one knew what he wanted. Wealth? Reputation? Power? These were not worth mentioning in his eyes. However, other than that, the search results did not provide more information about the Infinite Apostles and the Twelve Battle Maidens 'home.