Wait isn't it because she wants to be free? From her duties? Of course, she doesn't care at all about other people's safety, her selfishness is even higher than Dean.
Yeah that's right but the specific reason of why KIDNAPPING and LIA? For what reason? I can't seem to connect the reason for her wanting HER OWN freedom by taking Lia's life? I mean it not just kidnapping is the main reason but she also seem wanting to kill Lia eventually..（￣へ￣）
Honestly I'm not so sure. She's not exactly the mastermind anyway, so she could just be following orders. As for Lia, she doesn't exactly WANT to kill her, more like, the plan is to kidnap her. And wtv happens afterwards, she doesn't care. Sold, killed wtv. Again, it's all about what SHE wanted.
She mentioned that she want Lia to disappear, although she appear not caring what happened to Lia. I think she's the mastermind, she somehow admits it during her meeting with the 4 lords. The other Remingtons don't have any magic and are just under orders so she's clearly the mastermind.
Angelique Remington didn't show any hint of being directly involved (not just suspicions or speculations) in the web novel until the time when..
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She invited the Easter nobles into their home and eventually escape to Easter along with her whole family (her children were forced to) but they'll eventually get caught and admit her kidnapping to Lia but won't state the reason why specifically, I hope we'll get the answer to this in the manga.