Things you realise
about the HP series when you re-read the books as an adult;

• Why was the
  Philosophers/Sorcerer’s Stone protected so badly that three pre-pubescent
  children were able to get through the defences? Yes, the plot needed it, but
  that’s just bad planning.
• Would the teachers have
  seriously been prepared to sacrifice Ginny’s life just to prove how bad
  Lockhart was as a teacher? That’s messed up. I don’t care how bad he was;  a student’s life was at stake.
• Hagrid is a good man and
  I love him, but you wouldn’t want him in charge of teaching children. Especially
  not around magical creatures (some of whom are very dangerous, despite Hagrid’s
  assurances).
• Child endangerment is
  apparently a non-issue at Hogwarts. Like, why did they keep the Whomping Willow
  in the grounds after Lupin graduated? That’s just asking for trouble.
• Come to think about it,
  was the Shrieking Shack even around before Lupin started at Hogwarts? How did
  they build it without anyone noticing?
• Why were the Hogsmeade
  residents bothered by apparently-violent ghosts, when Hogwarts has Peeves and
  the Bloody Baron?
• Flitwick and Sprout are
  probably the least problematic teachers at Hogwarts (also, according to JK Rowling, they were married at one point? I was
  surprised too…)
• Why did Dumbledore
  continue with the Triwizard Tournament after an auror (albeit someone
  pretending to be an auror) made it clear that Harry was in danger by
  participating?
• Viktor Krum seems to
  have a weird thing for fifteen-year-old girls (Hermione, and then later Ginny
  at Bill and Fluer’s wedding reception). Why hasn’t anyone aside from Ron
  pointed out how creepy this is?
• Luna Lovegood is
  wonderful. We knew this reading the first time round, but this just confirmed it. Also, she probably had a
  crush on Ron when she first met him.
• The Fat Friar is easily
  the most cheerful ghost to be around.
• On reflection,
  Hufflepuffs definitely seem to have the best Hogwarts experience. I mean, their
  dorms are next to the kitchens, and they never have to worry about passwords.
• Did none of the other
  teachers ever do anything about the way that Snape was clearly favouring his
  own house? Or his treatment of Neville? Or Hermione? Or Harry? Or any
  non-Slytherin students, for that matter?
• Did we seriously not
  pick up oln the fact that Ron and Ginny slut-shame and virgin-shame each other
  in HBP? Not
  cool, you two… 
• Also, how come Ginny
  never realises that she helped cause the whole Lavender-debacle by telling Ron
  that Hermione had snogged Viktor Krum? And then she has the gall to call him a
  hypocrite when he then tries to get over Hermione. Honestly, not cool, Ginny. 
• Did Hermione ever find
  out that Ginny had told Ron that? Was she angry? Did Ginny apologise? 
• Speaking of apologies,
  how come Ron is always the one who has to apologise to everyone-else, even
  though most of the time it’s not even his fault to begin with? His emotional range is more like a billion
  tea-spoons, if you ask me…
• Why does this fandom
  hate Ron so much for having reasonable and human responses to things, and
  having self-doubts and insecurities like most ordinary people?
• Hermione gets
  disturbingly OP by the last book.
• There is far more canonical evidence for Hermione
  being an abusive partner compared to Ron.
• Lavender Brown is
  unfairly maligned.
• JK Rowling really
  should have avoided making Hermione her self-insert. Not only does it make
  Hermione infallible, but it also prevents the character from having character
  growth outside of ‘be less judgemental to Ron’.