
From a different perspective, I find her petty or is it because I read too much reincarnation manhwa? She got another chance but her mindset is still of a child who wants to destroy her sister. What she had been doing was the same as her sister too. Its just her sister is better at first and for the second time she gain knowledge. I hope there's character growth, these childish mindset of revenge. Her world revolves around Mirielle to the point that she'll target Oscar just to "annoy" her.

To be fair Mielle is after Aria and will spent the next years trying to ruin her so Aria needs to gain allies, power and the upper hand.
I don't think Aria can just pacifically wait until she grows up to be able to go far away since we already saw that Mielle will go as far as to get her killed, so at this point Aria's actions are just self-presevation with a bit of justifiable spite.

think about how mielle bullied her, ruined her life, killed her mother and had herself killed. she's acting this way because she knows that even if she does nothing, mielle's jealousy will drive her to do horrible things to aria. of course she would want to fight back. also given that aria's personality has always been like that: an eye for an eye.
we're getting character growth through revenge. she used to hate studying but now does because she wants to win. she used to care only about her looks but now she's learning manners.
she used to be two steps behind mielle so she's taking every opportunity to be one step ahead.

I think it's not that easy to forgive Mielle if you think in her perspective and her status is really low so it's actually make sense that she's really desprate to get her revenge. And at her last moment Aria is trying to apologize to Mielle but ended up finding out that she's been set up this whole time..think about it, you can't beat mielle of you have a kind heart because as time goes by Mielle will use her fake angel appearance to gain symphaty so it's really a good thing that Aria turned evil and sly lol.

Still doesn't mean she should become a murderer. She states that she wants to have Miele beheaded, but that is just too much. She is basically the villain she sought to destroy, and even more evil because she is internally an adult and knowingly fought with a child to eventually kill her. Im all for her trying to be cunning and making sure Miele do not grow up as a threat to her. And I like her rubbing it in Mieles fake saint face. But having Mieles head is where I draw the line. Because, really, do you want Miele to die with satisfaction that Aria turns out to be evil and act as an innocent victim. Because in this life, Miele will be innocent, shes still a child! So if we go down this trajectory, our FL will be a bitch that killed an innocent girl. Which is exactly what the other Miele did. Basically, I dont want her to be all evil cos I dont want her to be like Miele. I want her to have everything she deserve and Miele to have her crusty ass realise that Aria is now the Queen, and live forever in unsatisfaction and jealousy as Oscars wife.

Like I get that she has trauma and wants revenge, but if she becomes exactly like Miele, then she is just another textbook villain and thus is not a protagonist. Sort of like Harlequin, but a Harlequin that becomes the Joker. Basically defeats her whole character development if she becomes an entitled Karen like Miele. So the moral of the story here is, it is okay to kill others for revenge and use others. An eye for an eye makes the whole world blind. Im all for her being the mature kid that thwarts and laughs at Mieles schemes failing. She doesnt have to turn good like a saint. Just a chaotic neutral force that is always one step ahead and lead Miele to fail because of her own mistakes. I dont want her to be like Miele and actively frame and murder Miele.

Mielle is not innocent, even from this earlier in life she's already trying to hurt Aria (all the bad rumors about her, the conspiratorial maids) and her actions will only get worse with time, Mielle is already on a path you can't change.
On the other hand, you can be a villian and be the protagonist, even more loved for it, like Hannibal Lecter for example. Heck there's lots of mangas here with the same premise "heroe is terribly betrayed and dies, goes back on time and gets revenge in a bloody way" and no one has a problem with it, since is the whole center of the plot.
Maybe the problem is that the reincarnation mangas with a focus on a female demographic are all the same: "villian dies, goes back on time and becomes a goody two-shoes mary sue", Doctor Elise is a great example of that. This kind plot is so overused that readers became accustomed to it and now is like the norm, so I get why Aria is not suited to your taste.
Personally I find Aria so refreshing as a character because she's different from the rest of the FL in these kind of mangas: she's still a villian and not a villian turned saint and that's what sets apart this story from the others.
Overall I hope you can have an open mind and give this manga a chance, since it seems like is gonna be a good ride. If not, you can always check the "reincarnation" tag that's full of good little reincarnated villians, believe me, I read it all (〜 ̄△ ̄)〜

"in this life, mielle will be innocent" I don't think so... it's been established that mielle's motive for being a fake is that aria and her mom got into their family. so unless aria and her mom never enters the family or go away, mielle would definitely pull tricks.
we'll have to see, since the "beheading" part might just be metaphorical or something but i personally don't mind if this happens
the title is virtues of a villainess so ofc she'd be evil
they never intended for her to be a "protagonist"
Im with the maid and the butler too. Please hold a wonderful wedding ceremony