honestly i dont think that if cinder would grew as selene would be a bad person bc she'd have winter and jacin w her whole life and jacin wouldve soo protective over selene too like he was to cress
Hmm, it's a hard one to predict. She would've grown up around the pomp and circus of the royal court which would invariably rub off on her. Winter resisted that influence because her father raised her; but Selene has no one to raise her. In Fairest, she's looked after by nannies, and never is it mentioned that Evret or Levana took on a complete parental role for her. We see that as a 2-year-old Selene is described as having "hair too frequently uncombed", connoting that she was often neglected, even by her nannies.
Earlier in Fairest, Channary and Levana discuss the way they were raised by nannies and ignored by their parents. But they never fondly mention a nanny in particular or regard one as their parental figure. So although these nannies care for the royal children's physical needs, there is no evidence of a lasting, reliable parent-child dynamic. This isn't their fault; as lower-class workers they would be barred from too closely influencing the 'perfect' royalty.
Selene would therefore grow up without a parental figure, and while Winter and Jacin would have some good influence, it wouldn't be enough to entirely mitigate the negative influence around her. Becoming the queen at only 13 would heighten her distrust in people, as the court would likely sneer behind her back about how a child should not wear the crown. She would struggle to understand social dynamics as she never learnt how to make emotional bonds with adults, and therefore become emotionally reclusive, clinical and calculating.
As we know, in Levana's regency she begins accelerating production in the outer sectors--rapidly depleting Luna's resources. If Selene had to take over a kingdom on the brink of collapse, that emotionally-distant mentality would allow her to make unjust decisions without remorse. Perhaps Winter and Jacin could dissuade her to some extent. But consider: they are her only reliable sources of love. Once they pair off as a couple, she could be jealous and angry and betrayed, and eventually, their pleas for her to be lenient would go unheard.
In all, Selene may not do things from a place of malicious intent, but all the same do them ruthlessly. Certainly not the same good-hearted Cinder we know.