One interesting plot could be that in his Titan form, Eren has a special connection with Mikasa. Maybe he can communicate with her telepathically only when in Titan form. This could lead to them working together more closely in battles, with Mikasa being able to anticipate Eren's moves better. For example, during a fight against a horde of Titans, Eren's Titan form sends a mental signal to Mikasa about a weak point he's discovered on a huge Titan. Mikasa then uses this information to take it down swiftly.
The relationship might also be depicted as a source of inspiration. Eren's Titan form could inspire Mikasa to be even more fearless. She could see his strength and determination in that form and strive to match it. And in return, Eren could be inspired by Mikasa's unwavering loyalty. This mutual inspiration could drive the story forward, with both of them growing as characters throughout the fanfiction.
A great Eren Yeager OC fanfiction I read was about an OC who was a half - Titan. This OC had to hide their true nature from everyone, including Eren at first. But as the story progresses, they reveal their identity to Eren and together they try to find a way to end the Titan curse once and for all. It's full of action, drama, and explores the complex relationship between humans and Titans in a new way.
The idea of Eren Yeager in a harem scenario is interesting because it takes a character from a serious and often dark story and puts him in a more light - hearted, relationship - focused situation. It allows for different character interactions that we don't see in the original work.
The manga and anime of Eren Yeager have some similarities and differences. In some key plot points, they align closely, but there are also minor variations in character development and pacing.
There are various 'Eren Yeager x Harem' fanfictions. Some stories could be about Eren being in a harem situation where he has to balance his duties and his relationships. Maybe in one, he is training to fight Titans while also navigating his feelings for multiple girls. These fanfictions often play with the existing character dynamics and create new scenarios for the characters to interact in.
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.
One popular fanfiction idea could be a story where Eren has to team up with the Female Titan against a new, more powerful enemy in the world of Attack on Titan. Maybe they start off as reluctant allies, but as they face challenges together, they begin to understand each other better and develop a unique bond.
First, think about your OC's personality. Are they brave like Eren or more cautious? Then, decide on their backstory. Maybe they come from a family of outcasts within the walls. Next, consider how they will interact with Eren. Will they be friends, rivals, or something else? After that, plan out the plot. It could be about a new threat to the walls that only your OC and Eren can face together. And don't forget to give your OC unique abilities or traits that will make them stand out in the story.