Fighting for both sides of the same coin here

I understand where you are coming from, and I agree that is not hard being in her position, but I cannot sympathize with her, because her position in the story is so conflictive that it overrides any regard I have for her as a character. She is not Claude's daughter. She is not Athy's sister. And her intention to keep clinging to those positions and thus creating the conflict she is creating for no good reason, completely nullifies any sympathy I can have for her. I understand it is not her fault of course, but I like Athy significantly more, and the fact that Jeanette's very existence is a source of stress for Athy, when it doesn't have to be (because all of the things she thinks she is and deserves are not true), really puts her on my bad side.

I don't think the author is asking for sympathy for Jeanette, but instead making it clear that she isn't an enemy. Also, I'm pretty sure in the novel/original of this webcomic, she is actually Claude's daughter or somewhat related to him. She also isn't aware that she might not be his daughter, mainly because of her eyes, which I think everyone forgets that she doesn't know anything about the plot of the story.

I see where you're coming from, but recently I've been thinking about this:

Since Jennette did not reincarnate with her past knowledge, we can say that her character has stayed exactly the same as it was in their first life. Now, this information is important because we can see how she would act once she has everything she wants. In the first life, she has the love of her father (she thinks Claude is her father), she has a lovely sister, she marries the guy she wants and he is literally perfect, she becomes a princess, she gets new clothes and a whole palace just for herself. So, what does she do? She sees that Athy's palace/items get taken but says nothing, she notices that Claude acts bad towards Athy but does nothing, she sees that everyone favors her even though they're both princesses and she does n o t h i n g. She has the affection of Claude, so surely if she said some nice words about Athy to Claude, Claude would start to see Athy in a different light. We can see that she's also a bit possessive? Like when she saw Ejekiel and Athy talking she got upset because she doesn't to share Athy OR Ejekiel.

Also I didn't write this paragraph to hate on Jennette but to analize her character.

In the original she is not Claude's daughter either. Also, in the novel she actually is an enemy and tried to harm Athy

say it louder for the people in da back this was what i’ve been tryna say

This is also a really important aspect of her character. However, since we've seen that she feels her only place in the world is to be a princess, the product of said psychological manipulation, what happens when that comes true for her? Like I've said, she's not the brightest person and is extremely naive. Her only goal is to be loved by the emperor, and she does receive it, which takes away her only reason for doing pretty much anything. Since she's so naive, I doubt it ever occurred to her that Athy was suffering or wasn't loved, or she could even assume that because she has the emperor's love that she has the perfect family and nothing could go wrong if Athy died or went away. Jeanette often doesn't have the foresight for her actions and I'm assuming that she was blinded by what she was given.