These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Liz. She traps the others in the hole to make Mike fall in love with her, which indirectly causes the deaths of Frankie and Geoff. When Mike finds out, he ends up being killed (albeit accidentally) too. After she escapes the hole, she murders Martyn in order to pin the blame on him.
Magnificent Bitch: Liz. At the end of the movie she has pinned her own messes on the deceased Martyn (whom she killed) and the police psychologist, leaving her free to go and in an Alternate Ending find another boy to obsess over, this time calling herself 'Beth' and having dyed her now-long hair blonde.