Well, Jeannette grew up sheltered by the Alpheus House for the sake of easily controlling her so you can't blame her. She has no vigilance and very trusting that's why she easily trust Anastascius whom she just met and doesn't question Roger Alpheus' intention.
She is annoying, though.
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She is being use from the very start for the sake of taking the throne. From the first timeline to the current. She didn't know anything, always kept in the dark. If you think about it, disregarding whatever existing impression you have of her, she is the most pitiful among the characters. Her birth and her very existence is only for the sake of greed of others.
I agree ... I mean I know that that was what she was told that he is her dad and she also wished to get his love but ... she is very naive to think its true... its kinda hard to see how she doesn't get anything happening around her ... like how she gets happy to meet claude even though she knows that athy is in such a difficult position where she has to run from her home and dad .. so even if she did nothing wrong directly I kind of hate the existence of her....

Y'all WTF I just read chapter 62 and I fucking hate Jeannette.
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She's called at the palace, dressed like a fucking clown, and has tea with Claude the same way Athy had the first time they met. Then she get permission to stay at the palace and visit her """"father"""". She then is all happy because Claude started to notice her and forgets all the suffering Athy has been through because c'mon, now that Claude is interested in her that's the important thing. Did I already say that I HATE her?
She already stole Athy first life, now she's doing it again. I don't care if she's naïve and innocent, that's not an excuse to be a dumb doll.