One possible fanfic plot could be that Eren has been planning this for a long time. He might gather intelligence about the Colossal Titan's weaknesses. Then, in a fierce battle, he manages to get close enough to deliver a fatal blow. This could be a very emotional moment for him as well, considering the history between them.
Well, sometimes he uses his titan's speed and agility to dodge the Colossal Titan's attacks and then strike at its nape. It's a classic way to take down a titan in the Attack on Titan universe.
One common theme is the exploration of the blurry line between friend and foe. Since the Female Titan is initially an enemy, fanfictions often delve into whether she can become an ally through her interactions with Armin. For example, Armin might try to convince her to side with the humans.
In the Attack on Titan manga, Armin is still alive. His character plays an important role and continues to be part of the story's progression. There are many close calls, but he manages to come out unscathed.
Another difference lies in the overall mood. Canon AOT has a rather dark, gritty, and often hopeless mood due to the constant threat of Titans. However, a friendly Titan fanfic would likely have a more positive, hopeful mood. It might explore themes of redemption for the Titans, or how their existence could be beneficial to the world of AOT. This is a complete departure from the doom - and - gloom feeling that often pervades the official AOT story.
The ending of the AOT manga was complex and had various elements that sparked intense discussions. It wrapped up some storylines but left others open to interpretation.
Yes, there are quite a few. You can try searching on fanfic websites like Archive of Our Own. Just type in 'Female Titan x Armin' in the search bar and you'll get a list of relevant fanfics. Some might be really well - written with interesting plot twists and character developments.
One possible storyline could be that Armin discovers a way to communicate with the Female Titan on a more empathetic level. He tries to understand her motives beyond just being an enemy. Maybe she has some hidden knowledge about the Titans that Armin needs to save humanity.
The AOT manga wraps up in a way that ties up most of the storylines. However, it leaves some room for interpretation and has led to different opinions among readers about the overall satisfaction of the ending.