Greatwater Lake she was afraid of dreadful prophecies

scylla listens, ears pinned forward with true intrique. perhaps if it had been any other soapy tale, she would not have been as interested. but this was a true dramatic tragedy riddled with love (or a lack of it) and murderous deceit -- but it was subject matter of the latter that kept her attention. jealousy is a beast in slumber. maybe what you percieved as jealousy was her version of restraint. she can somewhat empathize with the unnamed sister, if not, understand how being cast as the underdog could easily clash with the instinct to survive. to many, a recipe for rash actions. 

anyways, i would call someone with the gall to maim their own brother weak. violence can be cowardly... illogical... but not weak. many might disagree but it was a belief she formulated based upon the observations of her own father. he had been violent, often stupid and brash, but never weak. however scylla did not want to assume she knew what intent ran through his sister's mind. it was not her place. just a theory. the girl concludes with a light shrugging motion. perhaps you can ask her why before serving your revenge.