Yes, there might be. The Naruto and Attack on Titan fandoms are both huge, and fans often like to cross over their favorite characters in fanfiction. So it's quite possible to find Eren - from Attack on Titan - in Naruto fanfiction. However, it may not be as common as fanfictions within each respective universe.
In the 'baby peter interrupts avengers meeting fanfic', it could be that baby Peter has some sort of special power that activates during the meeting. He might accidentally use it and cause chaos, like making Captain America's shield fly across the room. Or he could just be a normal baby and poop at an inconvenient time, making everyone scramble to deal with it while trying to keep the meeting on track.
First, be patient. Then try to understand why the kid is interrupting. Maybe they have a question or something exciting to share. Address their concern and then resume the story.
Some fans are heartbroken. Eren is a very popular character, and his death can be a huge emotional blow. They might write comments expressing their sadness and disappointment.
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.