The package that Derpy had in her mouth was wrapped in satin of deep magenta, tied with a ribbon that Karyn could see at once was real gold. If the exquisiteness of the packaging were not enough of a giveaway, the blazing Sun logo on the side made it clear who the sender was.

“Good morning, Derpy. What does Princess Celestia have for us here?”

“She didn’t tell me, but I’m prepared to trust her implicitly now.”

“After she was so nice last time, I’m sure. But why haven’t you opened it yet.”

Derpy put it on Karyn’s play desk and showed her the tag. “It’s not just for me. It says right there, ‘Derpy and Karyn.’ I wanted to wait until I saw you.”

“Well, I don’t want to keep you in suspense any longer. Go ahead.”

Derpy pulled on the gold ribbon with her teeth and it came loose. “Can you do the wrapping? I might rip it and your hands are so much more precise.”

“Of course I will.” Karyn found the flap and lifted it. She got off the paper in one piece, then Derpy opened the box and pulled out the object in it. It was like one of the spells Derpy kept in her saddlebag, but more sleek. If Derpy’s spells were like sneakers, this was like a high-heel pump.

“Hm. Why couldn’t Princess Celestia just cast this spell herself?” asked Derpy.

“It must be for our use on Earth. Hang on, there’s a letter in the box.”

The box was lined with more satin, and it was easy to miss the note among the fancy fabric. Derpy pulled it out and read.

“Ladies. In accordance with your willingness to expand your understanding of each other’s worlds with my guidance, please use this spell. Its effects last twenty-four hours. Sincerely yours, Princess Celestia.”

“Well, that wasn’t very revealing. Let’s use it and see what happens.”

Derpy put her hoof in the spell. “Brace yourself. Anything could happen.” She turned her hoof. “How did you get the spell?” she said.

“I have a few better questions. Why am I gray? What happened to my hands? Derpy, I’m a pony!”

“But then, what. . . “ Derpy held her hand in front of her face. “Oh, wow. The spell exchanged our bodies!”

“It did? I was not prepared for this.” Pony-Karyn’s voice was now deep and slow.

“I guess it won’t be too bad, if it’s only for twenty-four hours.” Human-Derpy took a step and face-planted the bed. “Wait a minute. I can’t fly!”

“Of course not. You’re me now.”

“How do you live like this?”

“I manage,” pony-Karyn said. “But how am I supposed to do, well, anything?” She waved her hooves in front of her, trying to pick up anything that was lying around, without success.

“Twenty-four hours like this? We’ll never make it.”

“Sure we will. We’re supposed to learn about each other, so let’s show each other how we go about our lives. Here, go ahead and try to use your hands.”

“To do what?” asked human-Derpy.

“Um. . . why not try writing something?

Human-Derpy picked up a pen on the working desk and held it in a fist. She put a piece of paper on the desk and tried to scribble on it. “This isn’t working!” she said. She dropped her hands onto the keyboard of the computer and saw some gibberish come up on the screen. She reached for the backspace key. “Oh, wait! Now this I can do! Oh, wow. No wonder this is your cutie mark! If I could do this, I’d never stop.”

“What exactly are you writing?”

“Oh, just anything that comes to mind.” Pony-Karyn came over and looked at the screen. It was filled with stream-of-consciousness words that made no sense, but human-Derpy kept typing.

“I should dictate and have you write for me. We can start by telling Princess Celestia just how appreciative we are of her gift.”

“I thought you didn’t like it.”

“When I’m back in my own body, remind me to explain sarcasm.” Pony-Karyn trotted around the room. “What am I going to do since I’m stuck as a pony?”

“Well, if nothing else, there is the fact that you can fly.”

“Yeah, big deal—wait. I can fly?”

Human-Derpy pointed her finger at pony-Karyn. “Yeah, you see those wings on your back? Use them.”

Pony-Karyn turned her head, amazed at the range she had with her neck. As she looked at her wings, Derpy’s wings really, that she was borrowing, she realized that a dream common to all humanity was in her grasp.

“How do I do it?”

“OK, this is really complicated. First, spread your wings.”

“Got it.” The pair of wings unfolded behind her.

“Now flap them.”

Pony-Karyn hovered off the ground a foot, then floated down to the ground. “That’s supposed to be complicated?”

“If that’s all you want, no. But if you actually want to get somewhere, you’ve got to understand about wind, air pressure, all sorts of aeronautics.”

“You know what? I’m happy just to have my feet off the ground. Or, my hooves rather.”

She flapped her wings again, then kept going. She smiled and laughed, bouncing up and down on nothing.

“I’m glad you’re enjoying yourself,” said human-Derpy, “but don’t count on making the Wonderbolts any time soon.”

“I just want to go try this outside!”

“Whoa there, little pony! Did you forget that we’re on Earth? You have to go invisible if you want to fly outside.”

“No, that’s you. Wait, no, it’s me now. Ah, I’m so confused!” Pony-Karyn put her hooves on her head. “I guess I’ll just stick to flying around the room.”

She took to her wings again. By leaning forward, she was able to get slight forward momentum. She enjoyed zooming around the room for a few minutes.

Without warning, she had a change in her vision. The pony started flying with exquisite skill, dipping and turning. Without thinking about it, she said, “Wow, Karyn, you’re getting good at that. Wait a minute, I’m Karyn. What’s going on?”

It took a moment of disorientation, but after that passed, both she and Derpy realized that they were back in their own bodies. “What’s going on?” said Derpy. “I thought it was supposed to last twenty-four hours.”

“So did I. Maybe this is part of the time difference thing. Twenty-four hours might have passed in Equestria while less time went by here.”

“That doesn’t make a whole lot of sense. Get that note again.”

Karyn found the letter from the princess and passed it to Derpy. “I was kind of getting used to flying,” she said. “Maybe we should try the spell again.”

“Doesn’t look like we’ll have to. Here, on the back. ‘Note that the twenty-four hours are not necessarily consecutive.’”

Karyn laughed. “I love Princess Celestia, but sometimes she can be so exasperating. Still, I’m sure she set it up so that we get to experience each other’s lives thoroughly.”

“Maybe we should get a stopwatch so that we can count up and know when the spell runs out.”

“I think we’ll be able to do it by rule of thumb.” Karyn wiggled her thumb, glad to have it back. “But I do wish that we had a schedule. What happens if you’re flying along and all of a sudden you turn into me? Or I turn into you. You know what I mean. Your body won’t be able to fly.”

“I trust you to land it safely,” said Derpy.

Just then, the phone rang. Derpy looked about, not used to hearing the noise, but with her movable ears tracing it to the instrument by the bedside. Karyn walked over and looked at the display on the back. “It’s my mom. Don’t worry, this won’t take a minute. Just keep quiet.” She pushed the call button, and watched in panic as the blonde girl on the other side of the room brought the phone to her ear. She and Derpy had switched again.

“Um. . . hello,” human-Derpy said.

“Hi, Karyn dear,” the voice on the phone said. “How are you doing?”

“Great, can you hang on a second?”

Pony-Karyn had torn across the room and tried to take the phone away, but she wasn’t used to her hooves and dropped it on the floor. Trying desperately to push the mute button, she quickly realized that she would never be able to get it. She whispered, “Quick, push this button, the one with the little circle-slash on it!”

Human-Derpy still enjoyed using her fingers, so smiled as she pushed the button. “Got it.”

“What are we going to do?! I can’t talk to her with your voice. We sound nothing alike. I can’t even pretend that I have a cold. You’ll have to hurry her off the phone as quick as you can.”

“No problem.” Human-Derpy pushed the button again. “Hi, Ka—I mean, Hi mom!”

“What was that just now?”

“Oh, I dropped the phone. I’m such a butterfingers.”

“I see,” Karyn’s mother said. “How’s your day going?”

“Just fine. Having a fun weekend. How’s yours?”

Pony-Karyn covered the receiver with a hoof and whispered, “This is what you call hurrying her off?”

“Trust me.” She pulled the phone away. “It’s good, I’m good.”

“Are you all right? You seem distracted. “

“Huh? Yeah, I was getting ready to go out. It’s a nice day, you know?”

“It is a nice day,” the voice on the phone said. “All right, you go enjoy it. I’ll talk to you later. Love you, bye.”

“Good-bye.” Human-Derpy put the phone back on its cradle. “See, talking about the weather always ends a conversation. Unless it’s between weather ponies, and I know that your mom isn’t a weather pony.”

Pony-Karyn went to sit down on her desk chair. She tried to sit human style, found it very uncomfortable, then tried putting her back hooves on the seat and leaning over the back, but that was still awkward. She jumped off and glided to the ground.

“Can we please go to Equestria? If I’ve got to be stuck as a pony, I at least want to be where everything is built for ponies.”

“Sure we can. Let me get on your back.”

“Well, this is going to be a switch.” Pony-Karyn knelt down and felt the weight of human-Derpy on her back. She was surprised at how little she weighed. “If carrying my body is this easy, either you’re, like, superpony or I’m free to snack between meals whenever I want.”

“I don’t think I’m that strong. Ponies like Applejack are much stronger than I am.”

“I’m sure. OK, walk me through this. What do I do next?”

“Open the saddlebag,” human-Derpy said. Pony-Karyn looked around. “On your right flank. It’s the first spell in there. Good. Now put your hoof into it. Wait! Don’t turn it yet.”

“Why not?”

“Because we always end up in the air. Don’t forget that and panic. Just flap your wings after you do activate it.”

Pony-Karyn braced herself and activated the spell. Pumping her wings intensely, it was more like stepping onto an elevator than the parachute jump she feared. They hit the ground with a dull thud of hooves.

“All right,” human-Derpy said, “Let’s go home.”

Trotting toward the house, pony-Karyn felt the usual stares of ponies around. They always noticed the human in town, but she now realized that they had just as many odd looks for Derpy. Whether it was her eyes, her clumsiness, or her friendship with a human, the body she was occupying was an object of attention as much as hers.

When she reached Derpy’s front door, she finally got to see how ponies had adapted to not having hands. The latch was activated by pushing against another part of it. Whoever had built it, not having an opposable thumb, had added a mechanical one.

They went in and sat down. The couches were wide and deep and provided plenty of room for the pony body. But human-Derpy was having problems of her own.

“This isn’t comfortable. Why is your back so weak?” she said.

“Well, you have to sit human style. Put your backside under you.”

Human-Derpy twisted around to the position. “Oh! This is easier on my neck. I don’t have to crane to see things.”

“Oh, and aren’t you supposed to have vision problems? I can see just fine out of your eyes.”

“And I’m fine seeing out of yours. Maybe the spell knew enough to transfer that for us.”

Just then there was a rustling and a cry from the next room. “Muffinhead!” human-Derpy said.

The ginger cat walked into the room with his tail up. “Hey, little one,” pony-Karyn said, “maybe today you’ll let me pet and cuddle you, huh?”

Muffinhead bounced up to her and sniffed around. She extended a hoof and gave him a loving stroke on his head. He backed off, narrowed his eyes, and circled around the room until he came to human-Derpy. He meowed.

“Aww. You still know your mommy, huh?” The cat hopped up on her lap and still looked confused. Carefully she used her hand to stroke his fur. Finally he started purring and smiling.

“I can’t win,” pony-Karyn said. “Did we switch smells too?”

“I think he knows my touch. I know the way he likes to be petted and—yeow! Take it easy, Muffinhead!”

The cat had extended his claws and was pawing at human-Derpy’s lap. He was penetrating through her denim jeans and knitting at her skin.

“Be careful with that body,” pony-Karyn said.

“I see why you wear clothes all the time. Your hide is a lot thinner than mine is. And more sensitive as well.”

“Yeah, but that’s not all bad. We can tell heat and cold faster than you can probably.”

“It’s true. And I do get more sensation in these hands than in my hooves. But why are your ears paralyzed?”

Pony-Karyn thought about that. “Actually, there are a few people who can wiggle their ears. I think anyone can learn if they really put the effort into it. But there’s no point. We hear well enough just by turning our heads or our whole bodies toward whatever the sound is.”

Human-Derpy nodded and moved her head for practice. “It’s also weird having a round head instead of a normal one. That reminds me, speaking of round.” She reached down and pulled up her shirt. “About these things you have.”

“Isn’t it about time we switched back randomly?!” pony-Karyn said.

As if she triggered it, Karyn found herself back in her own body clutching her chest. She quickly recomposed herself and smoothed out her shirt.

“How much longer do you think we have to go?” Derpy asked.

“The better part of the day still.”

Muffinhead jumped down off of Karyn’s lap and walked over to Derpy.

“You could tell we jumped back, huh?”

“I guess it could be worse,” said Karyn. “We could be on a three-way rotation with him as well.”

Derpy laughed and trotted off to the kitchen. “I’d better feed him.”

Karyn was left alone on Derpy’s couch. She ran her hands through her hair and stretched her arms. She had taken for granted the feeling of her own body for a long time, but now, after having taken a vacation from it, she was grateful just to feel her hands.

“Hey, Derpy. Do you think we should write or go see the Princess? Tell her that we don’t really appreciate this?”

“We did say that we would help. Is it really so bad being a pony? Or is it that you don’t like me in your body?

“It’s not even that,” said Karyn. “I just wish she had told us outright what it would do and how it would be scheduled. And as much as I love magic, I prefer it when you’re wielding spells than being the object of them.”

“I know you like using them yourself though. If we switch again while we’re not together, feel free to use any of mine. Most of them are labeled.”

“What about the ones that aren’t?”

Derpy looked at her bag. “I guess don’t use those. They should be safe though. Mostly safe.”

Karyn appreciated the gesture. “And you can use my computer if you’re in my room. Just don’t go crazy re-writing other people’s systems.”

“I promise.”

“And at least we know it does have a time limit. We’re not going to be switching back and forth for the rest of our lives.”

Derpy had busied herself tidying up the house, when the switch happened again. “Come on, Karyn,” human-Derpy said. “Let’s go out into Ponyville. We’ll see if anypony out there can tell that we’re switched.”

Still slightly reluctant, but not wanting to let her body out of her sight, pony-Karyn agreed. They started walking out of the house, when she said, “Do you want to ride?”

“Really?”

“Yeah. I find that I like carrying you. When I have the strength, I want to use it.”

Human-Derpy mounted. “And I have to say I enjoy it. It’s harder to keep balance with only two feet on the ground. If I had always been human, I think I would have just kept on all fours.”

“It’s not nearly as comfortable as you think.”

They reached the marketplace. “Is there anything you need me to pick up for you?” pony-Karyn asked.

“Hmm. . . I did notice that I was low on cat food.”

“OK, lead me to where I get that.”

“It’s at the far end,” human-Derpy said.

Pony-Karyn smiled a little. “At least you didn’t just pull my mane or look for reins to guide me.”

“Of course not! Why would I?”

“Remember that horses and ponies on Earth aren’t that bright. Humans have to guide them by gesture instead of just telling them where to go.”

“Maybe I need to teach them a thing or two,” human-Derpy said as she dismounted. “OK, go to that far stall and ask them for the cat food. I’m going to browse around for a few other things.”

“You’re not coming with me?”

“I’ll be along in a few minutes. Don’t worry. You’ll blend in fine. It’s me who everypony will be looking at.”

Pony-Karyn watched her own body walk away toward the other sellers. She found the booth that had been indicated and trotted up to it.

“Could I please have a pound of cat food?” she asked.

“Why so formal today, Derpy?” the pony behind the booth asked. “I know what you get.”

“Well, actually, I’m not Derpy. I’m her human friend, Karyn, stuck in her body by means of a spell that Princess Celestia sent us to see how we would react.”

The sales-pony burst out laughing. “Oh, that’s a good one! You always make me laugh. Here you go. That’ll be twenty bits.”

Karyn ran through it in her mind. She remembered that sometimes the vendors were willing to haggle. She wasn’t experienced at negotiations herself, but it seemed to her that, if a bit was about a dollar, that twenty was overcharging. “Twenty? For one pound?”

“A pound? I don’t think it weighs more than a few ounces.”

Karyn blinked as she realized that she was talking to a different pony. The cat food seller had been a pink mare; this was an orange stallion. She was back in her own body.

She looked down in her hand. There was a pendant in the shape of a dragon’s claw. She was confused until she saw Derpy flying toward her.

“That darn spell! It chooses the most inconvenient times. Now the surprise is ruined.”

“What surprise?” Karyn asked.

“I’m buying that for you.”

“What were you going to use for money? I don’t have any bits on me?”

“Oh, right,” said Derpy. “But it’s for you when you’re stuck as me. I’ll wear it, and whenever we switch you can look at it and remember that you have fingers instead of hooves.”

She reached into her bag and found the twenty bits, and passed the pendant onto Karyn, who clasped it around Derpy’s neck.”Thanks. Even though it’s kind of for you.”

“Are you going to go out and buy a pair of wings to wear for when I’m in you?”

“Not costume wings, but wing pins are popular. People will just think I’m a pilot or something. I might do that,”

“Come on, let’s get home and give this to Muffinhead before we switch again,” said Derpy, holding up the bag of cat food.

As they walked out of the market and the booths thinned out, Karyn said, “What’s the cat food made of anyway? Aren’t cats carnivores?”

“Yeah. There are a few farms that have chickens and pigs and lambs that are used for animal feed. We know that there are carnivores, we just can’t eat meat ourselves.” She looked at the bag. “Hmm. . . I guess I could try to see what eating meat is like when we’re switched.”

“Don’t you dare! I can, but I don’t, and I don’t want you to either.”

“I’m just kidding. I wouldn’t. Either I’d hate it, and that’d be no fun, or I’d like it, and know that I’d never get to do it again. Whatever happens, I’d be unhappy.”

Karyn was relieved and calmed down. They made it home. “All right, Derpy. I guess I’d better go home. We’ll meet up and compare notes next week. Take care of me, and I’ll take care of you.”

“Good luck,” said Derpy. She held out her hoof and shook Karyn’s hand.

Next week: the swaps come fast and when they least expect it!