I don't know what to make of it, honestly. When I first saw it (on late night, and I stayed up till three AM watching it), I thought it was a little like "A Clockwork Orange".
Graham Young (Hugh O'Conor) I found an odd mixture of three parts: curiosity (what leads him to poisoning), clinical detachment (as he watches the results), and a longing to belong (when he tries to be normal -and fails miserably).
First he silently threatens everyone with a gruesome retaliation for the slightest things, and then charts their decline with frightful accuracy as they get sicker and sicker. After that, he retreats into his den again until something better comes along. And then he gets caught.
Then there's that uproarious scene when he's out with a girl, and he tries to get her in a conversation on disembowelment. You can almost see her turn green as he gets into stride. To him, it's an innocent thing; something he likes. For her (and for us, the audience), it's...sick.
I thought that the rehabilitation sequence was a farce. It's as ludicrous as the rest of this quirky gem of a movie, with great performances by all the actors, particularly Hugh O'Conor. He says more with his eyes than most could with their lips.
I mean, the movie is funny (not ha ha funny, though), dripping with corrosive irony. Young is all at once twisted and innocent, torn between conforming and that endless fascination with poison. The comparisons between this and "Clockwork" are almost inevitable, but unlike Kubrick's thriller, this one has a more subtle, menacing tone, for the mind rather than for the eye. It's not a laugh-out-loud film, though it's undeniably hilarious. Whatever you feel, it's kept inside.
If you're one with a sensitive stomach, suicidal tendencies, strange addictions, goody-goodies/puritans, then stay away. Otherwise, WATCH THIS FILM!