you can have complex feelings for a character. shes not a good person, and shes not innocent, but at the end of the day she was just a very young and naive woman who did what she could to survive. i think that is what is easy so sympathise with. shes not a black and white character, shes not all good or all bad.
Tbh, I wouldn't have felt remorse or anything if she was not a slave ans the fact that slavery is legal there. And Navier and the emperor were not completely innocent on this. They did not abolish slavery even though they have the power. (Doesn't justify her actions of killing those people tho so I still kinda hate her but overall, it mellowed down)
Why are people suddenly feeling sorry for rashta? I don't understand. She deserved a worse end tbh. Having a tragic past doesn't give you a free pass to be a biotch.