User blog comment:Raised By Wolves/Top 10 Contestants Who Deserve Victory/@comment-4389268-20161217022337/@comment-5231983-20161217025448

She was faking being upset in France so Cody would notice her. That was awesome, btw.

It's not a question of her mental stability. Every character in this show is a caricature of the label they represent, and Sierra is no exception. She just happens to have a personality of a type of person who is already very over the top in real life, that being fangirls. So she's an over the top version of something that's already over the top.