Even

Navier tried to help her but she only shows her arrogant behaviour towards navier thinking that she have the upper hand because sovieshu favors her towards navier

Please she was a dumb slave that only saw worst in nobles bc she was a slave. If your parents are abusing you and you only see that, you will logical assume it's that way for everyone even if you are out of that place. She wanted his favor bc she didn't want to end up at the same place she was and I understand that(I wouldn't want that either, if I was in her place). She saw everything through the diffrent lance than Navier, some that looks so perfect in her eyes ofc she would think she has upper hand and tbh she has. Navier comes from the golden spoon household plus Diamond on bc she was promised crown since birth. We know it's not all sunshine and rainbows but try to explain that to the slave that thinks it's perfect life. You can try but everything will go over her head

Telling Rashta that Nobles like Navier aren't prefect is like telling a kid that thier time in the school is better than work

I'm sorry for answering so much but I'm trying to explain it in the way I see it and I came with new ideas how to explain it better I think.
I think it's natural for her to get greedy, even normal person, well atleast I hav same problem, while playing a game I got really powerful and cocky and I kinda abused that power.
People like Navier and other people that were born with that power and wealth are different breed bc they had responsible adults to tell them how to act and behave but a person like rashta that grow up as a slave didn't have that luxury. Since young she wanted that wealth and power(well atleast normal life) that noble had and when she got it, she lost herself with power and was too scared to lose it(funny enough she lost it bc of that) and there was no one to stop her. There was sovieshu but he didn't care about her, maids are lower class than her now and they can't say no. Other people around her used her for thier benefits so she didn't have anyone to correct her but like I said she got in the end what she dervered. She had sad upbringing but that's not excuse for ruining people's lifes

I think it's perfectly normal to try and sympathize with Rashta, in the beginning of the story I felt the same way as you (now I'm just jaded that the plot is so basic, fight me). She is a slave, someone who's looked down upon, from the very bottom of the hierarchy - that's a sympathetic position by itself.
Anyone would want an underdog to change for the better, it's just that this author chose her to be a rotten mut instead of taking the opportunity and write something with more nuance.

The thing is Rashta had opportunities to change around. Lots of people that had her back but we never saw any of it blossom since she never trust anyone and always unintentionally see herself as victim aka everyone is against her mindset mode. Where every criticism is misinterpreted as "they hate me that's why they say I'm doing bad thus their words are invalid." Navier altho unwilling tried a handful of time and begrudgingly tried to stop Rashta get accustomed in court but both Rashta and Sovieshu took that as Navier bullyng and undermining Rashta. Lots of warning she ignored... NO ONE managed to convince Rashta of othermise. Emperor is trash but he did offer her a hand and had her back but he was ignored (author should have thrown him under the bus too. The unresponsible douche. That let Rashta, a completely uneducated and ignorant of court matters, no offence intended, loose with the empress title and power.). Later on Rashta being an empress, her win over Navier and Duke Edgy support got over head and she straightout imitated the horrible people who treated her bad when she was a slave and thought she could deal with everything by herself.

Just like in irl, no matter how much you knock at someone's door to offer help, if it remains close there's nothing you can do.

I tot agree she's is a victim and tot innocent prior the story and when she was a slave. I also think she deserve all the affection and spoiling she received. Heck, I even admit and applaud her misdeeds if it's for her and her kid's survival sake. It's fair game imo. Everyone in this story is freaking sneaky with ulterior motives ready to throw everyone under the bus. BUT I cannot agree that she remains so when she ill intentionally took the initiative to harm others for entertainment. Or do it out of pure paranoia. Having an empress who kill and torture people bc of delusions and entertainment is terrible. Absolutely terrible. A menace to everyone. I actually also think it's fair that Gloriem was taken away from her bc I'm sorry but her paranoia and delusion is dangerous for her kid. . It just wouldn't make any sense to call her innocent.