spoilers kind of
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I think the "raeliana" in beaboich's body knew of the fate of the original Beatrice (our MC in raeliana's body) (basically they switched bodies, but our MC recalled her past life memories during the switch) Because the original Beatrice had a perfect life with Noah, while the original Raeliana was set to die by her ex-fiancee's hands, the og rae switched with og bea to get that fortune (basically riding on beatrice's tailcoats for the goods). but since our mc changed everything, og rae is out to kill her so that she can get the goods (aka noah and fame)
this is what i've taken away from the many spoilers in these comments including some of my own interpretation (=・ω・=)
ooo.. it seems plausible.. i have another theory
i alwayz though that the magician told her that she need to kill the soul of the body she is in at the moment so she can stay forever.. she also seems to have some issues with the body they are both in pain.. i think one has to die so the other one can stay in the current body, i dont think beatrice is after noah perse.. i think she only want to be the star of the story and live happy ever after.. but above all i think she only want to live

the real realina is trapped in beatrice's body ok we got it but WHY THE HELL does she want to kill the current one I mean ... it's not like you will have your body back lmao