While part of my brain attempts to adjust to Sharaloth's theory of quantum celestial mechanics, the rest of me is biting the bullet and catching up to my current spot in VoD. This section opens by detailing Dawn, at this point a Canterlot street urchin, meeting Celestia for the first time and becoming her protege, after she swipes from the royal kitchen and unleashes a magical surge to protect Razor Wind from pursuing guards ('All this for a scone?'). While even at this point she is mainly focused on gaining power to for protection and respect, as opposed to her successor's pure admiration and thirst for knowledge, this is the most sympathetic we've seen Dawn, and seeing her latch onto the Princess as the mother she'd never had goes a long way toward explaining her desperation to regain Celestia's affection (as counterproductive as it is).
In the present, Twilight and friends (still minus Applejack- it's zap apple season) prepare for the summit-cum-optional-masquerade with the zebras, and after some Costume Porn Twilight frets once more about the fuss everypony makes over her due to her ascension, namely her guard company, led by her brother's old mentor Captain Lancer.
"No ma'am."
"Aren't I your princess?" Twilight asked in a tone rather piqued.
"Certainly are ma'am."
"Don't you have to do what I say?"
"Depends on what you say ma'am. If you tell me to charge to my death so you can get away from your enemies then I'll do it double quick. If you tell me to run away so you can face your enemies personally like, then I don't have to take a bit of notice. Now if you'll beg pardon ma'am, time is a wasting and I thought you wanted to arrive promptly?"
Rarity and Rainbow reassure Twilight that nothing is going to change among their group, at least...
"And all walls have doors in them somewhere," Rarity added. "After all it isn't as though you abandoned books as soon as you made friends."
"I'll say not," Rainbow laughed.
Twilight shook her head, but said nothing. What could she say, after all? You don't know what it's like to be me! Nopony can understand how hard my life is, wah! That would have been the worst kind of self-centred, self-pitying nonsense. The truth was, as long as they were still her friends, she could put up with any circumstance.
Rainbow complains about not being allowed to perform another Sonic Rainboom for the party. Twilight notes that zebras aren't all that keen on flight:
The gang finally arrives, and, as with the Grand Galloping Gala, they soon scatter for their own interests (Rainbow getting much more opportunity to talk with the Wonderbolts, while Twilight notes that Spitfire is as much of a mentor to Rainbow now as Rainbow is to Scootaloo), before Twilight meets up with Shining Armor and Cadance.
Twilight shrugged, "Nopony has risen up to tear me off my throne yet so I guess I'm doing okay."
Turns out only zebra nobility speak in rhyme, which makes Twilight wonder about Zecora. The Quaggai delegation is cordial enough, but the Grevyian ambassador, Lord Mathos, walks in and complains about being made to wait to enter after so much travel, while using forms of address ill-suited for a supposedly higher-ranking counterpart ("Honored" instead of "Revered" implying equality, and patronizingly using "commoner" prose instead of poetry as the nobility would do amongst themselves). Celestia serenely lays the smack down by "apologizing" in rhyme, making Mathos knock it off lest he be seen as the "commoner" instead, though she notes to Twilight that this looks to be a long night.
Jumping back a bit, we see Dawn preparing to infiltrate the reception with Laurel. Cherry Blossom once again expresses uneasiness with the plan- specifically, removing Twilight's support network by attacking ponies (i.e. "the Princess") who haven't done anything to Dawn personally, but Dawn notes that she'll set things right for Twilight's "pawns" as soon as it's all over. Sure, the Tears of Nightmare Moon don't have any known antidote, but no doubt Laurel will succeed in a few weeks of research where generations of chemists have failed.
Back at the reception, the waltz starts up, Dawn asks Laurel onto the dance floor, and I honestly don't know if it says more about me, the writing, or the fandom that I'm unsure if this is supposed to be a Friendship Moment or Les Yay:
"Is it worth the wait?"
"Oh definitely," Laurel said. "You're an excellent dancer. You deserve a better partner."
"You're the best partner I could ask for," Dawn leaned in, her head touching Laurel's own. "You look beautiful tonight."
"I look average where I normally look plain," Laurel replied.
"No," Dawn said firmly. "You're beautiful. In my eyes at least."
Laurel laughed, "Keep this up Dawny and you'll turn me red."
"Thank you," Dawn said, touching the tip of Laurel's horn with her own. "I couldn't do this without you."
...until she bumps into Princess Cadance, spilling the alicorn's drink and offering her own in replacement.
Much later that night, Shining returns from drinks with his old guardmates to his and Cadance's guest room in the palace and attempts to join his wife in slumber, only for her to wake... and cry out in terror at this pony, and this place, of which she can remember nothing.
So Celestia was spot on. This is going to be a long night....