Grandpa ruins everything

"See, that is the foremost and truest mistake of storytelling.  Children, take heed; there has never been a good and proper tale with the preface once upon a time-"

"Grandpapa, please!  Just tell the story!  Tell the tale of beautiful princess!"

"Aye, Grandpapa, and the dreadful Uilepheist!  And his diet of nasty harpies!"

"Oi, and don't forget the beautiful, lovely princess!"

"'Ey, lot, why don't you all tell it since you've shouted the entire storyline?  Patience, little gremlins, it wouldn't kill you all to learn a bit about the nature of stories and faerytales.

"Now, what was I.. right, right, the garbage of once upon a time.  Phtooey.  The sorry-sod to start that wretched ritual ought'a be stoned for shaming the whole affair of yarn-spinning.  No good tale begins-"

"But Grandpapa, what about the tale of the mermaid princess?  That tale began with once upon a time!  And it's my favorite - no, second favorite, to the glass-slipper princess!  She's my favorite.  And that started with it too, yeah!"

"Little Ethel, I've got some terrible news."

"..What, Grandpapa?  Have you got lumbago?"

"Eh?  No.  You see, the tale of the water princess, the precious tale of love and triumph over wickedness and other blasphemy?  It's been mutilated from its true version.  It's a sham, a false idol in the pantheon of legend and fable."

"A sham?!  Even the bits about true love?"

"Especially the bits about true love.  Listen here, little gremlins; faerytales have naught to do with love, altruism, or utopian ideals.  The true nature of a faerytale is an expression of lore full of intrigue, beguiled by magic and pre-ordained misfortune.

"And the truth about that water princess, little Ethel?  She was penultimately spurned by the prince and died a virgin."