Louise Collins's non-series prison series

Is the title too confusing? I think it is. Let me explain. Louise Collins wrote three books where the plot takes place in different prisons. Apart from that they are not connected in any way, there are no common characters, they don't know each other, it's not even the same prison, but I can't help thinking about these books as part of a series simply because they are so similar.

The novels are, in the order they were published, The Freshman, The Psychopath, and The Rat. I first came across The Psychopath and I read that, afterwards I saw there were two more books and decided to read those as well, so I am going to go ahead and mix them up a bit next. 

First I'm going to say a little something about each novel and what I thought about them, then I'm going to compare them a bit.

The Psychopath 

When I read The Psychopath I enjoyed it a lot, there was tension from the first chapter an...