I dont think she is that bad of a person. Remember the end of chapter after meeting princess and the emperor, she looked up at the sky smiling while thinking about the two. I think she might know that she is the emperor's daughter, and she wants to be a part of the family with her beautiful dad and sister. So thats why I think she cannot stop her urge to be with them, so she approached the princess. However, I think its a tragedy for both of them as I read the recently raw, Jeannetter's dark power due to the experiment is somehow in the bad for the princess's magic. Thats why whenever you see they are encounter, after that the black hair magician kid has to remove something and she feels her body getting lighter. Well, I still want the magic kid with the mc though, he is the only one who can help her control the magic anw ╮( ̄▽ ̄)╭
I know that the mc knows but if Claude knows about it too then I just find it sad. Does it mean he knew about Jeannette not being his daughter in the book? According to the book that the Mc read before she reincarnated into Anthanasia, Claude never acknowleged her as his daughter and killed her when she was 18yrs old. Instead, he loved Jeannette and treated her as his "daughter".
In the novel, Athy was a timid shy girl and is the one who killed his beloved during pregnancy due to her extreme magic power, so he hates her and wants to kill her. This part didnt mention in the novel the mc reading but it does happened according to the dream the mc had. So thats why the mc doesnt even know why Claude hates Athy so much to kill her. So I think thats why Claude didnt even care if he has one more daughter, Jeannette or not. When I think about it, maybe Claude was using Jeannete to put Athy in a shameful situation to torture her. After that, Claude's just using the excuse of Jeannete being poisoned to kill off Athy because he hates her so much. Poor my Athy
ヽ(`Д´)ノ However this time, the MC try her best to get attachment to Claude for surviving so his point of view changed. ╮( ̄▽ ̄)╭
I have a feeling that Jeannette is just pretending to be "nice". After all, Jeannette does know Mr. white's "plan" towards Anthanasia and Claude but still approaching them purposely; trying to be innocent. Remember when she gave back Anthanasia's ribbon during her debut? Mr. white even scolded Jeannette saying "why did you approach them when you didn't have a plan?!"