The Supernaturalist is a Sci Fi novel by Eoin Colfer. In the future, 14-year-old Cosmo Hill escapes from the Clarissa Frayne Institute for Parentally Challenged Boys in an accident that nearly takes his life. He is saved by a group of teenagers calling themselves "The Supernaturalists" because they seek to rid the world of strange, alien-like creatures that they call "Parasites" and believe are sucking the life out of the wounded or dying. However, they soon discover a horrifying secret that turns their world upside down and gets them caught in a web far more complicated than anything they've ever imagined before.
Arson, Murder, and Jaywalking: "Abracadabra Street was no great challenge for a squadron that had broken into several foreign banks, two crime lords' strongholds, and a private kindergarten."
Dark Is Not Evil: Those Parasites sure are creepy, aren't they? As our heroes discover, however, they're more benevolent if anything, and it's not life they eat, it's pain. The Parasites exist to eat the pain of the dying so they'll have a more peaceful death.
Dystopia: According to this book, the future will behold a polluted, enviromentally destroyed planet, where sunsets are purple because of smog and technology is god.
Magical Defibrillator: Stefan restarts Cosmo's heart by shooting him in the chest with a Shocker round "strong enough to fry a rhinoceros" (notable for being much more powerful than the weaker versions used against the Parasites).
To be fair, though, he had just had thousands of volts go through him and his heart was in fibrillation.
MegaCorp: Satellite City seems to be controlled by Myishi.
Near Death Experience: Each of the main cast has had one; it's also the only way to see parasites.
Nice Job Breaking It, Hero: Subverted. Stephen is quite horrified to realize that the shocker weapons he thought were destroying the parasites were actually causing them to multiply, but then it turns out that the parasites are actually quite a benevolent species, so this wasn't as bad as Stephen thought.
Noodle Implements: Cosmo has a nightmare involving Ziplock, two parasites, and a hair dryer.
Sci-Fi Writers Have No Sense of Scale: The titular satellite of satellite city is described to in a geosynchronous orbit 50 kilometres above the earth. Little wonder then they are having trouble keeping it up…
It could be intentional, given the two apparent mistakes (gettable-to with low-orbit spaceplace, and about to fall down) cancelling each other out.
Supporting Protagonist: Cosmo Hill is the protagonist, the story is far more Stefan's story.