The Secret Garden/YMMV

The book:

 * Anvilicious, but Some Anvils Need to Be Dropped: The book takes several Author Tracts towards the end to smack the idea of "Go outside and run around in the fresh air, and if you think you're ill it'll make you ill and if you think you're healthy it'll make you healthy, and believe in the Magic!" But then again, who can wholeheartedly argue with that kind of Aesop?
 * It Was His Sled: On the first time through the book, Colin's existence is quite a shock.
 * Jerkass Woobie: Colin and Mary both, pre-Character Development.
 * Purity Sue: Dickon, Susan, and probably Lilias. Still, it's not very noticeable, especially with brats Mary and Colin to balance them out.
 * Too Dumb to Live: Mary's mother might have survived the cholera outbreak if she hadn't delayed her escape to attend a dinner party.
 * Toy Ship: Three-way Toy Shipping.
 * Triang Relations: Type 11. Make of that what you will.
 * The 1993 film plays this way up. You can almost feel the U(non)-ST coming off of Dickon and Mary (swing scene particularly), and Colin flat out says he wants to marry her.
 * Unfortunate Implications: "You're not dying! You just need to go play outside!"
 * Values Dissonance: Well, 1911, British Empire, "blacks," etc. -- but for something even more jarring just because it's less expected, count how many times Mary, a ten-year-old girl, is bluntly referred to as "ugly." By both the narrator and other characters. Often to her face. Also, compare the approving references to her getting fatter (i.e. healthier) with today's obesity paranoia.
 * Also, this: "She used the wrong Magic until she made him beat her."
 * Wangst: Colin is like this until Mary gives him a good talking-to.

The various adaptations:

 * Crowning Music of Awesome:
 * The 1987 version uses Chopin's Nocturne in E Minor, Op. 72, #1 as its theme music.
 * The 1993 film has some very beautiful theme music, too.
 * Designated Villain:
 * The 1993 film and the anime series designate Mrs. Medlock as an overbearing caretaker, even though in the book her initial antagonism fades as the narrative progresses.
 * The musical designates Neville Craven, a doctor who wants Colin to die so he can inherit his brother's estate. In the book, he is in fact a deeply caring man who took up medicine to help his older brother.
 * Granted, it's not quite stated, merely implied by an accusation from Mary. He's still the primary antagonist, though.
 * The anime series not only does this to Medlock, but
 * Die for Our Ship: The 1987 film has a bit of this outside of the story. Since the film makers made it so, they had to get rid of . The only way to do that was to kill him.
 * The sequel to the 1993 version Back to The Secret Garden also does this; Dickon  and Mary and Colin end up married. The only difference is that they're still related in this version.
 * Nightmare Fuel: In any of the film adaptations, Mary walking through the house to find Colin can be deeply unsettling. The 1987 version takes this Up to Eleven with scary music and a lightning storm raging outside the manor -- and let's not forget the cutaways to the light playing off of the dark, ugly statues.
 * There's also the opening from that same movie, where Mary's wandering through a house where everyone except her is dead or dying from cholera, and she doesn't even understand what's happening. Special mention goes to the lingering shot on Mary's dying parents, with their faces twisted up in pain.
 * Purity Sue: Arguably, Lillias Craven in the anime series.
 * The Woobie: The '93 movie gives us a dream sequence of a toddler Mary being abandoned by her mother in the jungle, and crying piteously. It's pretty heartbreaking.
 * You could consider that scene to be Foreshadowing for the end of the movie,.
 * The anime series gives us  She is epically broken, and it's a miracle she doesn't commit suicide or something and remains kind to Mary.