It took a while for Sera to digest her words, until it hit her completely. Katarina Douglas, the Empress Dowager that not only instigated the whole rebellion with her grandson, but also used Aurora as a pawn to create more chaos inside the Palace.
Sera could tell what it made Aurora feel. She had trusted the Dowager, treated her like a friend, only to find out she had been using her all this time. She had made Aurora to be the rumored mole, only for it to be someone else all this time.
It must have bothered you the most. Sera thought, looking at Aurora with pity in her eyes. To be accused of something you didn't do. Perhaps that is why you had spent your time looking for the true mole, only for it to be a Lanterburian this whole time.