Isn't it. She was the one mainly driving events, had already been excluded from one school for some drug-related reason, was the one mainly planning the MO of the murder, and had a story meticulously worked out in the event that they were caught. There was a whole trail of WhatsApp messages showing this in detail.
On the pretext of befriending her would-be victim, she then used this friendship to go ahead and murder Brianna. She then said in court that it had all been an elaborate fantasy and she didn't think for a minute that Radcliffe would actually go ahead and do it. Thankfully she wasn't bargaining on the joint enterprise argument and the intent was clear enough to the jury.
She's extremely cunning, devious and manipulative - particularly in the way she seems able to persuade others to do her dirty work for her. There's no question that if she hadn't been caught she'd have gone on to kill again.
Fifteen years old. How the hell does a person become quite this fucked up at so young an age?