In Being Human (the original British series) season 2 episode 3 “Long Live the King”, Cara kills some teenagers after Mitchell has ordered that there should be no killing of humans. The teenagers are apparently an opportunistic target: we see Cara seeming to fancy them in a mall, and Cara isn't the subtle type. Yet Chief constable Wilson implies to Mitchell in one of their confrontations that the victims were targeted as they all had prior run-ins with the police. So was this just a coincidence that Wilson does not believe in, was there some deeper plot that Mitchell failed to uncover, or am I missing something?
First let me say, I was attempting to clean my house while I was watching this episode, so I certainly wouldn't take my interpretation of this as gospel. However, I too was a little intrigued by this particular scene and I re-watched it.
I was under the impression that Cara's hunger was completely out of control by this point. I recall she observed the teenagers at the mall, and they appeared to be bullying another girl (playing keep-away with the girl's purse or something to that effect). Just from Cara's appearance, it seems to me that she was probably a girl who was bullied/picked on before she became a vamp.
Then the scene changes and you see her killing one girl, but she walks away and leaves the other unharmed (possibly the girl who was being bullied? I'm not 100% sure). It just seemed more personal than random to me, but maybe I'm overthinking it.