It's not her fault 

Ares turned to Stella right after he heard her mature but cute voice being replaced by that rude tone. He got dumbfounded, not knowing whether he was hearing the same person from before or not. 

'W-What's it? What happened to her angelical cute face and gentle, yet distant eyes?' Ares thought, flabbergasted. 

"Oh? So you finally showed your true personality to the world, huh? I thought that you wouldn't hold yourself for longer after seeing your darling getting insulted..." Hera said with a smile of contempt on her face. "I hate people like you, you know? People who keep wearing masks to hide their true personalities, hiding as well what they are capable to do and their real intentions."

"And I hate traumatized people who think that they are more intelligent than others just because of hierarchical rankings and this kind of shit!" Stella shot back with a frown and grim eyes.