Book the 13th
Avid followers of "A Series of Unfortunate Events" sensed that "The Vile Village", the seventh book in the series, would be the turning point in the tragic saga of the Baudelaire orphans. Mr. Poe won't accompany the siblings to their new guardian, who happened to be a distant relative. A community would look after them instead. The children won't be able to call Mr. Poe when in trouble. Uncle Olaf, who was eager to snatch the children's fortune, became audacious and more cunning in his attempts.
Daniel Handler didn't foresee a series when "The Bad Beginning" was published on September 30, 1999. The first chapters revealed a troika of young children in a humongous home. They lost their parents, which was the worst thing that could happened to them. And there was something about the omnipresent eye. Victorian setting, absurd premise, mystery, nothing new about it. But the author knew how to pique a reader's curiosity.
The narrator warned the readers about the misery haunting the Baudelaire orphans, even advising them not to read further if they couldn't take it. But they would ignore it. Call it reverse psychology. Expect curiosity to make them think otherwise.
Dramatic irony, and a combination of other things
Handler resorted to gallows humor, while telling this sob tale. Writers like Shakespeare have used it, often to highlight the irony of a situation. This was the case of the Baudelaire orphans, and the readers were unable to tear their eyes from the pages. Another reason would be the author's penchant of explaining certain matters. Not that the readers wouldn't figure it out, as this was a literary device that turned "A Series of Unfortunate Events" into infectious reading.
Handler, who is distantly related to British writer Hugh Walpole, would remind readers that they're looking at real incidents. Who can play with the Incredibly Deadly Viper? Who wants to drive through Lousy Lane? Who can come close to the Lachrymose Leeches?
The Baudelaire children almost sealed their doom after the staging of “The Marvelous Marriage”, where Violet, the eldest of the brood, would sign the marriage contract. It happened that her hair was arranged in a way suggesting deep thinking. She managed to outwit Count Olaf, who turned out to be a horrible relative. He and his dreadful troupe would follow them anywhere they go. The siblings were happy with Uncle Monty, a devoted herpetologist, until his new assistant, Uncle Olaf in disguise, came knocking in the door.
As the chapters progressed, readers were hoping there won't be an end to the children's misfortune. Count Olaf knew how to put a spell on anyone, readers included.

