@TheElusiveIdiot
Spoiler!
Well for starters the ML is the white haired boy, Ethan.
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Apperantly Theon was using her as a means to control his power which is some sort of dark spirits, however it only worked when her brother was near. That's why he went through with the marriage in the first life, I guess. Ethan seemed to have discovered some secret related to Theon's power and since then in the first life, didn't like him because he realised he was using our FL.
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Ethan seems to have also regressed with her, and at a ball she recognizes that, and she accepts his feelings and they get together. It seems alot of things went wrong with the killing indiscriminately in the first life, this was mostly because of Ethan. He found out that the FL's life was similar to his thus fell in love with her. Therefore, he sought to put her on the throne no matter what, because he believed she had the makings of a good empress. And to make sure that she sat on the throne he killed whoever and whatever that got in her way without regards to what people would think about that.
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As for the father I haven't a clue, I haven't seen anything related to him.
"I dreamt for so long. My flesh was dull gold... and my blood, rotted. Corpse after corpse, left in my wake...- Heed my words. I am Malenia, Blade of Miquella. And I have never known defeat."
