Maybe I'm lucky, but any time I've owed someone less than $500 for what I've used (marijuana and ecstasy) they just didn't give me more. One timed I owed $1700 to one guy and he basically said if I didn't give him the $$ owed he would reimburse himself with items he found in my garage or home. Yeah, gave him that cash right fast. Maybe if I haven't have it could have seriously escalated.
If it was a drug debt related kidnapping, I HAVE to assume the person would have A) already wanted Sierra in this situation so he could get what he wanted from her B) the person was addicted to substances they are selling or C and D) The person made a living selling or owed someone ELSE money on what she owed them.
Given the utter craziness which drugs inevitably lead to, it could well have been ABC and D...or a combo of them... Sierra has been described by LE as being "strong willed " which can be both a good and a bad thing, depending on the situation...JMO Mostly I think she was a vulnerable 15 year old girl...anything could have happened. Another poster said that they thought she was "naive " and I could see that too... JMO