When a universe dies, it's tragic, but at least it's over.
When a universe almost dies, but is saved at the last moment... things get messy.
Cracks in the nature of reality still abound, leaving physics somewhat malleable, which can result in serious logistical issues. Swathes of time and space might have dangerously low levels of existence, making crossing them an exercise in insanity. Even in realms where there is a deific clean-up crew scrambling about to keep things stable, certain minor issues (like insane dictators) might go unnoticed because, excuse me, I'm keeping the SUN FROM BLOWING UP can't you overthrow that tyrant on your own, thank you!
This is, of course, all before going into outside factors. Like, say, echos of other realities sinking in more due to a thinner universal shell. Or interdimensional bandits taking the opportunity to plunder a few hundred souls. Or unique forms of magic that would normally never be part of the reality suddenly cropping up in certain instances.
Or the scavengers.
A universe has an awful lot of energy, an awful awful lot. And energy, in all its forms, is fed upon by life of some sort. It's a cosmological constant. In the between, the realm where there are no laws of physics, merely suggestions, many strange creatures have sprung up that are perfectly content to consume the scraps of a dead universe. So if they smell one in the process of dying, they're going to gather like vultures. And if that dying universe suddenly stops dying, and starts getting better...
...well, it takes an awful lot of power to move to another universe. And being denied a meal can make any being just a little... tetchy.
"Oh come on, do you have to wear that hat everywhere?"
"Eeeeyup."
Rarity huffed. "This is a wedding, Applejack! And not just any wedding, it's the first official wedding ministered by Sunset's church!"
Applejack's look was so deadpan, skillets and stock pots alike started writing their wills.
"I mean, yes. I am a little surprised it's the... church of the divine bacon horse that has that honor," Rarity allowed. "It really is rather ridiculous. I would have assumed that a more, ahem, conservative branch of Shimmerism would actually have been more prepared to..."
Rarity trailed off, watching Applejack's slowly ascending eyebrow.
"...the point is," she rallied quickly, "most people consider wearing hats at a wedding to be a little, shall we say, disrespectful. I can allow the boots to get by, but the hat--"
"--is, accordin' ta Ruby, an iconic part o' mah image as one o' Sunset's favored. And since she's somehow tha pope in this whole heap o' nonsense, tha hat is goin' ta stay."
Rarity blinked.
"....You know, out of all of us, I never expected you to be one to exploit Sunset's religious following."
The corner of Applejack's mouth quirked. "Ah'm just followin' expectations. Don't want nothin' ruinin' things fer tha happy couple, after all." She shrugged. "Even if'n Ah don't know 'em personally."
"They're two of the bishops for the church."
"Yeah, well, only member o' tha church Ah keep in touch with is Ruby, and that's only cause she keeps in touch with me."
Rarity threw up her hands. "You know what, fine. I had enough of a hassle designing the dresses for the brides--for some bizarre reason they insisted on incorporating armor into their gowns. Actual armor!" She gave an exasperated sigh. "At least I got plenty of practice with that after Rainbow's little stunt... speaking of, where is that ruffian?"
As if on cue, a blue figure rushed into the room, impossibly skidding to a stop in midair. "Guys! Look, I know this is going to sound crazy, but there's a giant weevil crawling over the mountains!"
There was a moment where they were all quiet, even as the rest of the wedding staff continued to set up the tables around them.
"Alright." Rarity held up a hand. "Let me just see if I understand you. A giant weevil is coming in from the mountains."
"Yes!"
"And we're supposed to think this is crazy... why?"
Rainbow blinked. "Uh, huge bugs? Square cube law? Basic sanity?"
"Rainbow," Applejack drawled, "Ah don't know if'n ya noticed, but we're at a weddin' with our friend as tha patron goddess, where a good number o' people--countin' tha priest--can actually fly, and most o' the rest can do some sort o' magic. Also we're 'parently saints cause we're friends o' said goddess. And, let's be honest, we got a superhero as a principal, who helps run a global super hero network, and--"
"Alright, alright, fine, I get it, life is weird." Rainbow rolled her eyes. "Seriously though, giant bug. We should do something about that."
"Right, Ah'll go talk ta Sunset. Ah mean, Ah assume the Power Patriots have somethin' on that already, but might be best ta keep her clued in."
"Very good. Now, Rainbow, is this going to be a problem for your aerial routine...?"
Applejack rolled her eyes as she left the duo to bicker over details, walking through the crowd to the head of the room. She approached Sunset Shimmer, resigned to wearing some elegant flowing thing, and Twilight Sparkle, fiddling with gem-studded glasses, as they argued with Ruby Rose--an oddly young pegasus aspect whose outfit looked like a mix between princess, pope, and goth.
"...all I'm saying is that if you switch to your unshelled form now, we could--"
"Look, I'm happy for the two of them, and I get this is important, but the fact is I'm only here as the observer. I don't want to make any glorious proclamation that I don't have to make. I'll go full pony when the time comes, alright?"
Ruby sighed, adjusting the papal tiara in her blood-red hair. "I'm not asking you to make a proclamation. Part of the ceremony includes tying tresses made from your mane around the brides' wrists, and while I could cut your mane in front of the whole congregation--"
"'scuse me, don't mean ta interrupt," Applejack blatantly interrupted, "but somethin's come up Ah thought Sunset should be made aware of, just in case."
Sunset steeled herself, turning to her friend with a warm, if slightly forced, smile. "Is your bracelet acting up?"
"Eh, nah." Applejack glanced at the apple-shaped gem on her arm. "Whatever you and Ditzy did, that weird color magic ain't causin' no more trouble."
"What is it then? Protesters outside the church? A personal emergency? Yet another world-threatening force?"
"Possibly tha third one. Giant weevil comin' in over tha mountains. It's probably bein' handled, but Ah figgered Ah'd keep ya up to date..."
The other girl shut her eyes, masking their sudden glow. After a few moments, she opened them. "Well that's... an issue. I'm not seeing it... or rather, I'm not-seeing it."
"Uh... what?"
"She cannot detect the presence of the creature, but detects a void where the creature presumably is," Twilight translated. "Which is really kind of concerning, now that I think about it..."
"Yeah, it seems to be absorbing the local magic... could be a problem, and not one that I could fix." Sunset tapped her chin. "Whatever it is, it's attuned to the local magical sympathy, so normal spells are out."
Twilight hmmmed. "Is there a way to use alternative magical sympathies?"
"Yes, theoretically, but one would need foreign... magic...."
Both of them turned to Applejack.
Applejack blinked for a moment or two.
Then she sighed. "Ah'm gonna have ta have a right chat with Apple Bloom, ain't I? Alright, alright, the ceremony's not fer another half hour, Ah'll handle it."
"Thanks, AJ. Really appreciate it." Sunset turned back to Ruby. "Now, what's this about my mane being used in the wedding?"
"Well, the dual color is usually taken to represent Self and Other, so by tying their wrists with tresses from your mane it would symbolize the unification of..."
Applejack rolled her eyes as she walked away, clearing her throat as she passed by Rarity. "Not ta put pressure on ya, but Ah've been put on monster fightin' duty. Ah'll try ta make it quick, but mah dress might need a touch-up when Ah get back so--"
"Yes, yes, thank you for telling me darling, I'll be ready for it. As I was saying, Rainbow, you can't pull the whirlwind here, everyone has too much fabric--"
"I'm going to be up in the sky--"
"Yes, but that's no guarantee--"
The farmer rolled her eyes and walked out of the reserved banquet hall.