When Pinkie builds a time machine, Twilight warns her against using it.
When Pinkie builds a time machine to go back in time and learn more about her past, Twilight warns her against it because it could possibly change Equestria as they know it.
"Pinkie, what are you doing?" asks a curious yet cautious Twilight.
"Building a time machine," replies Pinkie.
"Why, though? Don't you know time travel is dangerous?" replies Twilight with a puzzled look on her face.
"I'll be fine, Twilight," replies Pinkie, "you worry too much."
"Yeah, maybe, but probably better safe than sorry, you sure you want to do this? You could change everything."
"I'm sure, Twi," replies Pinkie. "I've got to do this." She then hops into the time machine and pulls the lever. She then goes on to travel back, back, back, back, back, back, further and further in time.
"Be safe," sighs Twilight as she stares at the wall where Pinkie's time machine contraption used to be. "Be safe. Please." Twilight walks away to her home. All she can do now is hope and pray that Pinkie doesn't get herself stranded in time or does something she'll regret that will butterfly effect in their faces later.
Meanwhile, Pinkie continues to go back in time all the way to when her parents told her they were born. As she looks in the window, she sees a young Goldie Delicious rocking her infant mother. She then pops into a house across the street and sees another mare rocking her infant father and his brother on the floor at her ankles. Pinkie is stunned. She is part Apple after all. She can't believe it. She remembers Twilight's warning though, 'don't do anything you'll regret or anything that will butterfly effect later'. Now that she's seen where her parents came from. It's time to move on and learn how they fell in love. She hops in the time machine and hops forward in time to the day her parents first met in school in an old rock mining town as teenagers.
As she peeks in the window of the school, she sees her teenage father asking her teenage mother out on a date. Unfortunately, though, her mother turns him down which leaves him down in the dumps. He asks her again later that afternoon and this time, she gives in and says yes. She then watches as the two go on their first date. She's mesmerized. She watches as the two share a kiss.
Now, it's time for her to move on farther into the future, to the day of Maud's birth. This is one that she is particularly excited about even more so than going to see the twins: Limestone and Marble's birth later on down the time stream that she's cruising on.
A few more years forward in the time stream, Pinkie hops out of her time machine outside the small rock farm where her parents now live. She watches through the window as they rock an infant Maud that was just handed to them by a local doctor that must be a friend of theirs. Pinkie smiles as she watches her mother sing a lullaby to the infant Maud. Pinkie can't believe how cute her sister was as a foal! She can hardly believe her eyes and that, for once, she doesn't mind. She then goes into the little town several miles from the rock farm and buys something to eat. This event, her going to get food from the past, is about to mess up Equestria's future and she is completely clueless about it. All she wants is a snack and she figures, no way can a snack mess up the time stream as she knows it.
Crash! Thud! Everything around her begins to fall. She heads back to the time machine, jumps in, and returns to her time. She'll see the twins birth another day. Right now, everything is falling apart all around her. This is not how she planned it at all. She sighs. "Everything would've been fine if I had just listened to Twilight, then none of this would've happened." Indeed, she is right, if she hadn't gone into the past, none of what is happening now would've come to pass.
A few hours later, Pinkie's time machine pops up in Twilight's library. Twilight stands there stunned. Once the shock is gone, she begins to yell at Pinkie and tell her all that she did wrong. Pinkie breaks out crying. "I know I did wrong!" replies Pinkie, "I should've never traveled back in time! Who knew me just buying a muffin in the past would mess up everything? I sure didn't! I had no idea! You were right, Twilight!" She continues to cry.
"Does this mean you're not going to try it again?" asks Twilight.
"Yes," replies Pinkie, half lying, half telling the truth. "At least, possibly. I still want to see the births of Marble and Limestone, but that can wait until another day."
"Or wait until, how about never," replies Twilight with a scowl. She then slaps her face. She's remembering it's Pinkie and that Pinkie can only screw up more from here if she doesn't heed the warnings Twilight herself is currently giving her.
Three months later, Pinkie ignores Twilight's advice and goes back in time once again. This time, she goes to the date the twins were born and watches them be born. After watching the event, she goes and buys a balloon and a snack not caring about, but well knowing, the repercussions it will have in modern day Equestria.
Meanwhile, in modern day Equestria, Twilight watches as everything changes around her and she immediately knows it's because Pinkie ignored her advice and went back in time again. Twilight gulps. "We're doomed!" She gulps again. "We're so doomed!" All of a sudden, she realizes the wings she used to have on her back are now completely gone. This means that she never was supposed to move to Ponyville and that everything is changing and the change is kicking off with her. Not long after that, Twilight is found by guards and told to return to tutelage under Celestia in Canterlot. She goes and Spike goes with her. As they return with the guard, Spike soon vanishes and she can no longer remember what he looks like. She begins to cry. Pinkie has messed with things immensely and she has no clue.
Meanwhile, everything is happy at the Apple farm. Big Mack and AJ are frolicking around with not a care in the world and Apple Bloom is being rocked by her parents. Granny Smith has passed away and been buried in the Apple family graveyard. In Applejack's mind, everything is perfect, the paradise they never had.
Meanwhile, Rarity has dominated every city with a mega fashion empire and is the richest mare in the world now. Her face is postered everywhere. Everypony is buying her designs and she's featured on the cover of every single major fashion magazine in Canterlot, Manehattan, and the world. She couldn't be happier even if that means pushing her sister, mother, and father out of her life completely.
Meanwhile, Rainbow Dash has taken over the Wonderbolts and turned it into the Wonderbolts Trick Flying Corps. This means that she actually demoted then fired Spitfire and promoted Soaren to be her second in command. Her dream has finally become true. She couldn't be happier as she takes to the sky flying.
"Pinkie, what have you done?" Sighs Twilight as she bows her head and walks into the castle to greet Celestia for what she knows to be the hundredth time, but in reality, it's the first time the two will ever meet.
Meanwhile, in the past, Pinkie watches her mother and father through a window with Maud standing beside them as they rock the twins. She smiles. A few minutes later, Pinkie hops back into her time machine and returns to the now messed up modern Equestria.
A half hour later, Pinkie returns to the modern day Equestria but everything around her is different. Trixie has become mayor and her friends are nowhere to be found. "What have I done?" she says as a tear falls from her eyes. "I messed up everypony else's lives just to see my past. I'm so selfish, such a fool. What have I done?" she cries as she walks down the street and to Sugar Cube Corner. At least, that is still around. When she walks inside, the store is empty, abandoned. "What happened to the Cakes?" She then finds a note on the counter that reads: 'left town because we saw Trixie as a threat to our children. Good luck running Sugar Cube Corner on your own.' Pinkie breaks back into tears. Her time excursion didn't just mess up the lives of her friends but her family as well and now she feels terrible. She goes upstairs to her room and sits on her bed and cries. "What have I done?" she cries. "What have I done? Now, how do I fix it? I don't even know."
Meanwhile in Canterlot, Twilight is studying under Celestia. As she does, she can't help but cry. She can't believe Pinkie would ever do this. She thought Pinkie was her friend. Clearly, she was wrong. All Pinkie cares about is herself. That's clear to her now. She picks up another book and gets to work on practicing spells. She sighs as she looks down and buries her nose in the book. Her life is changed forever and it's all Pinkie's fault. She can't help but feel betrayed by her own friend.
Meanwhile at Sugar Cube Corner, Pinkie says to herself, "I'm sure Twilight hates my guts now and I don't blame her because I did go against her warnings. She was right, I never should have gone back in time. It's all my fault." More tears fall from her eyes. She wants her friends back, but alas, that's never going to happen all because she traveled back in time and now, everything is going to be this way forever.
The days dredge on and with each one Pinkie Pie gets more and more and more depressed with each one. At one point, she even tries to commit suicide but to no avail. Her good hearted nature and better judgement wouldn't let her. She sighs, "what have I done? What have I done? Everything is messed up now and it's all my fault." She then goes to her closet and looks at her cannon. She then takes it out and shoots it at her head. This puts her into a coma and she's rushed to the hospital once she's found by surprisingly, Applejack.
Nine months later, Pinkie wakes up from the coma and finds Applejack at her bedside. Honest to say, she's surprised. "Applejack!" she squeals. "You saved me that day I shot myself with my cannon."
"Yes," replies Applejack. "I may not know you personally but I couldn't just let you lie there and possibly die. No pony in their right mind would do that."
"Well, thank you," replies Pinkie as a smile comes across her face.
"You're welcome," replies Applejack before she leaves the hospital room and returns back to her family farm. She's curious as to how the pink pony knows her and she vows to get to the bottom of it as soon as she possibly can.
Meanwhile back at the Apple Family Farm, AJ sits on her bed in her room and puts her head on her hoof and thinks. "Do I know that pink pony in the hospital? Did I know her once? Why did she seem so familiar, like I've seen her before?" A few minutes later, Apple Bloom walks in.
"Applejack, it's time for the family picnic, let's go," says Apple Bloom. AJ nods and follows her sister to the back orchard where she sits down by her brother. The family then enjoys their picnic. They enjoy their hay burgers as they crack jokes and share memories and stories. After the picnic, the family goes down to the lake and takes a swim. Apple Bloom can't help but notice that her sister seems a bit spacey. She even brings it up. "Sis, what's got your mane in a twist?"
"Nothing, nothing," lies Applejack.
"Sis, I know you're lying," says Apple Bloom.
"Fine," sighs AJ, "I'll tell you. I took a pink pony to the hospital earlier and I can't help but feel like I know her even though I've never met her before in my life."
"It's a false memory, it's nothing," responds Apple Bloom.
"Maybe," sighs Applejack, "but it seemed to real to be a false memory." She then bows her head until she is surprised as Apple Bloom splashes down behind her and splashes her. Applejack smiles and begins chasing her sister around the lake. She can try to put the pieces together later, right now, she has a little sister to splash. She begins to laugh as she chases her sister and Apple Bloom can't help but smile. She's just glad her sister has gotten back to her spunky self because that is the Applejack she truly enjoys. This is the fun Applejack she remembers and she's glad that's the Applejack that's around right now. The two continue to chase each other around the lake now with Big Mac joining in on the fun. The three siblings smile as they swim about. Their parents smile as they watch. Everything is perfect. The family can definitely agree to that, at least, all the family can except Applejack, who feels like something doesn't seem quite right.
The next day, Applejack goes to Goldi Delicious to get some answers. She wants to know how she knows the pink pony in the hospital and only Goldi can tell her that.
A few minutes later, she arrives at Goldi's. She knocks on the door and Goldi lets her in. "Hey hon, what do you want to know today?"
"Can you tell me about a pink pony named Pinkie Pie?" asks Applejack. Goldi nods and goes and grabs a book with a balloon on the cover. She then opens it.
"Pinkie Pie is Ponyville's local baker and party pony. She's friends with everypony but her best friends are Applejack, Rarity, Fluttershy, Rainbow Dash, and Twilight. She knows everything about them and throws them birthdays accordingly."
"So I do know her and these other ponies?" says Applejack shocked. She then heads back over to the hospital to talk with Pinkie.
At the hospital, Applejack goes to Pinkie's room. Once inside, she asks, "do I really know all these ponies?" She shows Pinkie the book.
Pinkie sighs, "yes. We're all friends...or rather, we were. Once I traveled back in time, all that changed. Twilight warned me against it, but I didn't listen. I never listen."
"Well, you have to go back in time and fix it," says Applejack.
"Don't you see I can't? I can't unsee the births of my sisters. That's impossible. This is our current day now, but we can try to reunite everypony. Maybe that will fix things." Applejack nods. The next day, they head off to Canterlot to meet Twilight for what seems to be the first time in their lives but not before going to Fluttershy's cottage, grabbing her, Cloudsdale and grabbing Rainbow Dash, and Manehattan to grab Rarity. They do the same for the CMC as well. The group then heads off to Canterlot to get Twilight back.
A few hours later, the group arrive in Canterlot and hop off the train. They then head to the castle. Once they arrive to the castle, they notice a familiar unicorn sitting in the gardens. They enter the castle gardens and greet the purple unicorn with a hug.
"Girls!" exclaims Twilight happily, "Man! Am I glad to see you!" She hugs the rest of the Mane Six and the CMC. She then lets go of the embrace. "We need to figure out how to get me back my wings and fast. That should fix the time stream."
Twilight then goes inside the castle asking them to stay in the garden except for Pinkie Pie, who goes with her. Inside, the two try to explain things to the princess but to no avail. After several more hours of explaining things, Celestia agrees that something doesn't seem quite right and happily returns Twilight's wings hoping it will fix things.
The next day, everything returns back to normal. The friends are no longer separated. Granny Smith is back in the picture and it's Applejack's parents who are now deceased. Twilight getting back her wings has fixed everything. She's relieved and even helps Pinkie destroy the time machine with fire. Pinkie apologizes for her errors and all her friends forgive her. Pinkie's just glad to have them back and so is Twilight. Now, they can go on saving Equestria together once again and that makes them very, very happy.
