I will now copypaste my

posts from the spoiler thread - about 25 images, and some Fluts analysis.

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It's been awhile, but passive aggressive Fluts came out again in a way. Remember when she jabbed at Pinkie & Rarity with PYHD? She's still keeping in mind what she considers her friends' worst
internal fears, or as Fluts puts it, "core" fears:
Fluttershy: [spooky voice] Have a seat. Don't be scared of what awaits you. Go on. Pass the sugar. Oh, no! There is none! You're a terrible host!
AJ fails at being the honest farmer pony or whatever
Fluttershy: Rarity, put your coat on! You need to cover up because no one has complimented your dressssssss!

Fluttershy: Pinkie Pie, look to your left and ask your best friend to pass the cucumber sandwiches!
Pinkie Pie: Huh? I can't. There's nopony there.
Fluttershy: [spooky voice] That's right. Because she didn't care to show uuuuuup.
Pinkie Pie: What?
Fluttershy: [spooky voice] A friend who didn't come through. That must scare you to the coooore. Quick, everypony, look behind you!
I've seen people say that this matches Twilight in Amending Fences better than Pinkie, but that was Twilight's pre-show problem and who knows if she told the Mane 6 about it. Party of One, everyone.
Then she projects herself at the end:
Fluttershy: [spooky voice] They're unplanned guests. Your woooorst nightmare. You don't have enough food for them! Oh, no! There's a tiny kitten that needs a home! But you are over-scheduled right now. You don't have time to help! I said, "You don't have time to help!" This should appear to scare you! [normal voice] Why don't you look terrified? You showed up to a party and everypony was extremely disappointed in you. Can you imagine anything more upsetting?
Ultimately Fluts' first go-to idea of fear and scares is much more deep than the simple thrills of Nightmare Night, perhaps ultimately why she backs off of participating after this one year.