Thief?
Four days earlier, on the night Sol and Ikaris confessed and then erased the memories of everyone, Arla sat in her chambers, usually she would have cast a charm and prevented herself from sleeping as she worked on her magical formulas and new alchemy in her study, but she found herself sitting and staring blankly for an hour in her estate; after Renia had asked it was bothering her, something truly had been amiss.
Luckily for her, she was not alone, her staff was present, and while it did not carry sentience, it did carry memory, it held special magic inside of it that stored fragments of memory for whomever held it, so the moment she was sure she had been manipulated, she went to work extracting those memories, it took her an entire day, so she was only truly aware on the same night after the heroes challenged Sol.