Apologies for bringing up the photo again LOL I didn't want to discuss the photo so much as LE's "peek-a-boo" game with the evidence so far which is quite confusing, giving luke warm info, this might be what she wore, this car is "involved" etc ..
I don't want to disparage Sierra, because in fact I have a lot of empathy for her circumstances the last few months before she disappeared - but I do not think she was always the friendly natured girl as sometimes reported. Obviously it is only an impression and based on my own experiences. But if what I imagine of her is true, I cannot see her letting down her guard to "enemies" and getting in a car with them ... in her shoes I would not want to be vulnerable and show that I was prepared to be on friendly terms at their whim. Mostly I guess I just do not see her as being easily victimised by her peers ... victimised yes, anyone can be, but not with a lot of push back and not easily manipulated.
It really is awful that what seems like a turbulent and difficult phase for Sierra would have surely improved and resolved in time, she had a lot going for her, and instead some terrible fate has befallen her.