Fanfiction about Eren and Levi kissing can be quite interesting. It might explore a different side of their relationship. Some fanfictions in this regard could be about a moment of emotional intensity between them, where the kiss represents a deep connection that goes beyond their usual interactions in the original story.
Mikasa and Eren don't kiss in the manga. The focus of their connection lies in different aspects of their shared experiences and the evolving plot rather than a romantic kiss.