This was certainly a packed chapter!

It sounds as though Dumbo may find himself persona non grata in Gringotts very soon. I do hope so. I wonder how much money he has "appropriated" to himself. I'll bet it's a bundle.

I feel bad for Amelia. Knowing she has hurt and neglected someone she cared for has to be painful for both of them. I wonder why she didn't follow up Sirius's case when she had the authority to do it. Was she placed under compulsions NOT to do so by Dumbledore? Nothing he does or did surprises me, and I can see him not wanting her to pursue the case. She should check on that.

Will Hermione get a ring that protects her from Potions and spells?

Snape has tried to get through Dumbo's hard head, but Dumbo doesn't seem interested. I'm glad Snape has wised up and is supportive of Harry. Together, they should be able to make Dumbo's life very unsettled. He! He!

I'm surprised Emma is so anti-owl. Usually she is portrayed very open to and curious about the magical world.

You are enormously mistaken about the Attack on Pearl Harbour.
First of all, the Japanese did not meet (and thus also not destroy) ANY US carriers in the base, which was a core target of this mission too. And it would cause them endless problems over the rest of the war. Strike One!

Then they were detected early, through a midget submarine getting discovered. Only luck prevented the larger mission to be revealed before it could even begin (Hawaii also had Radar that with more experience and thus better qualified interpreters of the screen images would have betrayed the approaching strike force almost half an hour out from Pearl!). But they certainly did not plan on that to happen, so it's strike two on the "perfect plan execution" theory.

Finally their pilots diverged many times from the plans, targeted the wrong shipclass (destroyers instead of cruisers, cruisers instead of Battleships) and especially the Torpedo bombers totally botched up their approach vectors leading to only a small number of the big battleships being hit, far less than they planned and could have achieved if everything went perfect. Strike Three, and they're out!

And of course the whole mission, the idea of a "terminal strike" to destroy the US willingness to even start a war, as the samurai doctrine would demand, was thoroughly mistaken, just as Admiral Yamamoto predicted with his often quoted "you will wake a sleeping dragon" warning. Which lead to them following in the footsteps of Kroesus ... aiming to destroy a mighty empire... only to find that the ruined realm was his own!

So no, it went not 100% according to plan, on the contrary, Pearl Harbor is a perfect example of the "no plan survives first contact with the enemy" maxime. Chances are that with any mission for which you ASSUME the opposite, you just lack the detailed knowledge about how much went wrong to realize that it too fits in this pattern.

As for the rules of writing. They are not bound to commercial or leisure writing, they are bound to good and entertaining (or lackluster and not too thrilling) writing. Namely the first rule of ALL written stories, factual or fictional: the story needs adversity to be interesting. That can be persons you need to overcome, personal shortcomings or natural events you have to overcome. But in pretty much all of writing an unopposed protagonist is a boring "Mary Sue" type character.

You unconsciously even have bits and pieces that follow this iron clad base axiom of literature, the break-up of Amelia and Sirius for example. But by and large your story is designed as if it were an antihero Dumbledore's tale of his all time worst year, not Harry Potter's retelling of his best! Dumbledore gets all the opposition, all the obstacles to heroically overcome (and fails)

Harry and Hermione had their happily ever after.

Sirius and Heather will be happy together.

Hermione is, now, similar to Harry.

Harry is worried about Hermione.

Harry still has to destroy the diary, and kill Nagini.

Ermine has figured Harry out?

Hermione nearly slipped up.

Sev is dating Amelia.

Remus is in for some seriously hard choice making.

Hermione is going to try to reduce the length of essays.

Ron was, is, and always will be a Dunce.

Andi is surprised about the fact that Harry formed the “quod house group” of first years.