Sorry to dredge this up after so long, but I am just now seeing this comment..... I think... because I responded to the comment directly below it xD
Where does it say that Rosa's mother was a prostitute? We know that she was a commoner living in poverty and that she seduced her way into becoming Adonis's wife.
Think you missed the mothers activities when she met lord asshole while out on expedition. Couple that with Rosa herself being sired by a nameless sailor gives you a good picture of a barmaid that supplemented her income by sleeping with customers. True not exactly a full time sex worker, but she still sold her body for money.
And even then, what gave Rosa the justification to abuse and torture Aria?
Her mother. Her new position as the older child. Think there was also a pledge to herself about being the better person. Not in the sense of being nice, but in power and standing.
While people in poverty are more likely to commit crimes, most poor people are actually decent human beings that are just trying to get by in life. Most people do not go out of their way to abuse and torture someone else.
O . o;
NGL, this just comes off as an opinion of someone sheltered and nieve. Maybe an only child, from an affluent community? Anyway, while you are sorta correct that most don't go out of their way to abuse those around them, bullies and selfentitled asshats exist in all strata of society. And they tend to target those that are already different or struggling to integrate.
As shown above, Rosa is the bastard daughter of of a barmaid and sexworker. She is also a redhead with freckles. While that might seem like an odd point to make, there is a lot of stigma in Japanese culture about facial blemishes and hair color. So other then the flashback where Rosa was bullied by other kids, there is also alot of context in her physical charactistic that would lead a Japanese audience to understand her poor societal standing.
It is understandable that Rosa would be shocked by the revelation. But that still is not enough to completely thrown her own mother, that basically made her a princess, under the bus.
Children are fickle. They also tend not to have the emotional bandwidth to process much beyond the immediate situation at hand. So when you take a child who was previously abused or ostracized by the other children, give them tangible power over her new peers, and then this wonderful new existence is stripped away because that person lied... the emotional whiplash would be as dramatic and it would be explosive.
As a perent, I've seen it happen for much much less.