One possible reason could be a plot device to create drama. Maybe the author wants to show a rift between them for the sake of a more complex storyline. For example, if there's some misunderstanding or a secret that has come to light which makes Harry act this way.
Well, it could be for the sake of creating drama. In the Harry Potter universe, the relationship between Lily and Harry is a fundamental one. By having Lily ignore Harry, it throws a huge wrench into the normal narrative. This allows the author to explore different emotional responses from Harry, his friends, and other family members. It also gives a chance to rewrite certain aspects of the story, like how Harry might become more self - reliant or turn to different people for support.
It can add a lot of tension. For example, if Lily is used to Harry being friendly and then he suddenly starts ignoring her, it can create a sense of mystery and unease. Readers will be curious to find out why he's acting this way and will keep reading to uncover the truth.
There are quite a few out there. For instance, 'Shadows of Ignorance' is a fanfic where Lily is under a spell that makes her ignore Harry. The story is interesting as it not only shows Harry's struggle but also how the other characters around them react to this strange situation. It's a complex exploration of family relationships in the context of the Harry Potter universe. Another one is 'Isolation from Mother' which specifically focuses on the psychological impact on Harry when Lily begins to ignore him. The author does a great job of portraying Harry's confusion and sadness.
Maybe to explore an alternative scenario. In the original story, Severus has a complex relationship with Lily. By having him ignore her, it can create a whole new set of character developments and plot twists. It could also be a way to show how their lives and the overall story might have been different if that one aspect of their relationship was changed.
Well, I'm not sure of specific 'Severus ignores Lily' fanfictions off the top of my head. But you could also try Fanfiction.net. Sometimes the search function there might not be as precise as AO3, but it still has a vast collection. You might need to sift through a bit to find the ones that really focus on Severus ignoring Lily. It could be an interesting exploration of a different dynamic between the two characters compared to the canon.
Some writers might write this type of fanfiction as a form of character study. They want to understand the characters better by putting them in unexpected situations. For James, ignoring Lily could be a way to explore his pride, his immaturity at certain points, or his ability to resist his feelings. And for Lily, it's a chance to see how she copes with rejection and how it shapes her own character development. It also allows for different interactions with other characters in the series, like Severus Snape, who has his own complex relationship with Lily.
There might be a variety of such fanfictions out there. Some could explore how Lily reacts to being ignored by James, while others might focus on the reasons behind James' ignoring behavior. However, without a more in - depth search on the fanfiction platforms, it's hard to give you exact titles. But it's an interesting concept that many authors might have delved into.
Mrs. Weasley could get a bit angry too. She has a temper, and if she feels that Harry is being disrespectful by ignoring her, she might scold him a bit. However, her anger would come from a place of love and concern. She just wants Harry to be okay and part of the family, and his ignoring her goes against that.
In this kind of fanfiction, Harry might face various consequences. He could end up in dangerous situations all alone without the support and guidance of the Order. Maybe he stumbles upon a powerful dark magic artifact while on his own and has to figure out how to deal with it without the proper knowledge from the Order.