After Rashta dies in novel, there is alternative story. Where Sovieshu after finding her in forest instead taking her as concubine, send het to Navier. Empress made her maid. Rashta admire and respect empress dearly. She also meet noble from other kingdom, and they start developing feeling to each other. Sovieshu had one night stand with some random noble lady, and situacion between him and Navier start to develop i similar way to main story. Navier wants Rashta to let go with her crush, but she decided to stay loyal to empress, and say that she instead will go to western kingdom with her. For Navier it was confusing, as she did not know Hailey at this point yet. Later we discover that it was Rashta regretful spirit dream.
In main story arc i cant find any quote that, that show that Rashta purposely seduced emperor. It was more like other way around actually, as it Sovieshu claims her to be a his pray.