Author's note: It's been a while since I've updated this story—been busy with school. I would like to acknowledge a few people by username: AnimeLover217, Alexandria Prime, StoryFinder1, thor94. To you and everyone else who has left a review for my story: thank you so much for checking this story out. This has been fun, and it is knowing that at least one person is reading the story and enjoying it that motivates me to continue it.

I have to say, one challenge for me when writing this story has been thinking about point of view. Normally, in stories, only the thoughts and feelings of one character are explained by the narrator, but in this story, I've been shedding light into the thoughts and feelings of all characters, generally moving from one to another—a style called third person omniscient. At times, I've regretted this choice of POV. In the Sonic X anime, we are not given as much insight into Sonic's inner thought processes as I have given the reader here. In the anime, rarely does Sonic have asides in which he is the only character in the scene, speaking his inner thoughts. I think this gave Sonic a kind of mysterious side to his personality that I have not quite captured in the current story. In the anime, the viewer is often left wondering, Why would Sonic do that?, only to have an explanation told either implicitly through Sonic's actions or explicitly through another character's speech. Seldom, however, does Sonic explain himself directly. Food for thought. Maybe for a different story.

Also, it has occurred to me and probably to you that I have been giving little attention to Shadow since he and Sonic arrived in Chris's world. Rest assured, this is a temporary situation—the story revolves around his conflicts, after all.

A million thoughts raced through Sonic's mind. Topaz?! A G.U.N. agent? Have I met her before? Yes! She was with Rouge the Bat all the time. Can we trust her? She's an agent, so is she with that creepy agent I met last night? And she's coming here tomorrow?! Could she be spying on…

"Haha, you look surprised, Sonic," said Chris, interrupting Sonic's internal stream of questions. "I don't exactly blame you. Our jaws all kind of dropped open when Tanaka first walked in with her way back when."

Chuck chuckled heartily. "That was a real party," he said. "She was here not long before you arrived, Sonic. We were having a Thanksgiving dinner."

Sonic smiled. Sonic and his friends did not celebrate Thanksgiving in their own world, but they had good memories of celebrating it with a dinner feast back when they were in Chris's world.

Sonic laughed along, but inside, he was curious about Topaz and her relationship with the conspiracy within G.U.N. How do I bring this up…? he thought.

As it turned out, he didn't have to. Chris did so for him. "Hey Grandpa, speaking of government agents, did we ever figure out who those men in black were last night? The ones that attacked us, I mean."

Chuck shook his head. "They refused to say anything to the police, but they will be charged for multiple felonies, including attempted murder. We won't be seeing them for the rest of our lives, hopefully."

"Perhaps Topaz could weigh in…" mused Tanaka. "Perhaps I should ask her to come tonight for dinner instead of tomorrow."

Sonic gave a small sputter, and the others looked at him confusedly.

"Is something wrong, Sonic?" asked Chris.

Sonic shook his head vigorously. "No problem. I just kind of want to meet and talk with Topaz… about those agents."

Tanaka nodded. "Then it is settled. I will call her immediately."

Tanaka walked into another room to make the call, while Chris turned to Sonic, smiling. "Hey Sonic, want to go flying?"

The two headed for the garage. There, Chris pulled a lever, which caused the entire garage to lift up off the ground, revealing the hidden underground aircraft hanger beneath it.

"After you guys left, we kept the makeshift runway we have on our driveway," Chris explained. "I got my pilot's license, and now I can fly you wherever you want to go, Sonic! Today, let's look for those Chaos emeralds! It'll be like old times!"

Sonic's eyes widened in amazement as the palm trees lining the driveway moved aside to make room for the runway. It was a sight he had beheld hundreds of times, since Tails had used the design for his own runway back home as well, but seeing the grown-up Chris operate the platform single handedly added to Sonic's already overwhelming amount of respect for his young human friend.

Inside the aircraft hanger was a small two-seater biplane, not unlike Tails' original Tornado. Chris hopped into the pilot's seat and looked backwards, expecting to see Sonic hop into the passenger seat behind him. Instead of jumping into the passenger seat, however, Sonic decided to hop onto the top of the plane's wings.

"Uh, Sonic," said Chris. "I know you like to sit on the wings, but after taking hundreds of hours of flying courses, I have to say, that's really dangerous. The wind blows strong sometimes, and if you get blown off, I don't know if I'll be able to rescue you in time."

Sonic looked back to Chris, and to Chris's surprise, he gave an extremely wide grin. His eyes sparkled with excitement as he gave a thumbs up. "What are we waiting for?" he asked. "Let's go!"

Chris stood speechless for a second. Had he understood a word I just said? It suddenly occurred to Chris that Sonic did not realize Chris had been asking him to sit in the passenger seat. Chris had merely remarked that sitting on the wings was extremely dangerous, and Sonic, being the thrill-seeker he was, took that as if Chris was building excitement for the trip.

Chris determined he would not be swayed. "Sonic, I'm telling you, it's not safe to sit outside of the cockpit when flying."

Sonic looked at Chris with a pained expression, as if danger was a basic need that Chris was denying him. "It'll be fine, Chris. You don't have to worry about me. You said this'd be like old times."

Chris shook his head. This was something that he would have been perfectly okay with as a twelve-year-old, but now that he was an adult, he wanted to be more responsible. "Listen, Sonic. Back then Tails was the one flying, and back in your world Tails was almost always nearby when I flew with you. This time, Tails isn't here, so it's going to be my responsibility if something happens to you. We're going to be flying pretty high up this time, and I just don't trust myself enough to do stunt tricks with the plane without potentially getting someone hurt. I only got my pilot's license a few years ago, after all."

Chris's explanation did nothing to persuade Sonic, who only laid himself down across the wing in protest. After a few moments, he said, "Chris, I promise you I'm going to be okay. And I'm sure you're a better flyer than you think you are. Have I ever been wrong?"

"No, but this is seriously different!" said Chris exasperatedly, throwing his arms up in near defeat. "How about this. I'll bet you that you won't be able to stay on the wings the whole time."

As soon as the words left Chris's mouth, his brain reeled back. What the heck am I saying?!

Sonic's ears, however, perked up. "Deal!" he announced. "If I win, then I get to fly on the wings every time we fly together."

Chris raised a finger to reply, but then he retracted it, considering this thoughtfully. It was true that he did trust Sonic at least not to die, especially from such a ridiculous death as falling off a plane by accident, but he wanted Sonic to see where he was coming from. An idea came to mind. If executed properly, it would get Sonic to come around and sit in the cockpit, and it would let him practice a flying maneuver he had wanted to work on. It shouldn't be terribly difficult or dangerous either, given the special modifications he made to this particular aircraft. Heck, Chris figured he might throw in a more interesting penalty for Sonic if he lost the bet.

"Okay," said Chris finally. "And if I win, then you have to sit in the cockpit every time we fly. And, uh, you have to ask Amy out on a date the next time you see her."

Sonic fell off the wings of the plane right then and there. Shocked, he hit the ground and sat there for a few moments in stunned silence. He clearly did not expect this kind of behavior from Chris. Eventually, he turned back around to look at Chris, asking softly, "Wow, Chris. How did you get that idea in your head?"

Chris smiled sheepishly. "I, uh, was trying to think of things that would be embarrassing for you. Looks like I found something."

The sparkle in Sonic's eyes was gone, and his originally cheerful expression was replaced by a frown. At once, Chris felt ashamed. "I'm sorry, Sonic. You don't have to—"

"I'll take that bet," interrupted Sonic, looking towards the sky—Chris could have sworn that he saw traces of a blush on the hedgehog's normally confident face. "But if I win, not only do I get to fly on the wings every time, you have to ask Helen on a date."

Chris began to sputter unintelligibly. Unlike Sonic, Chris couldn't control the blood rushing into his cheeks as he blushed massively. "B-but, I—, How did you know—, Helen?!, Where did—, I—"

Sonic began laughing. "It's fair, right? You asking me to do that is like me asking you to do this. Amy's a friend to me like Helen's a friend to you. I'm guessing you won't take the—"

"I'll do it."

This, Sonic did not expect. Stunned, he gaped at his human friend, unsure of what to say.

Chris offered his hand for Sonic to shake. "I am betting you that you won't be able to stay on the wings the whole time we're flying," Chris summarized.

Slowly, Sonic outstretched his arm, clasping it around Chris's and shaking it firmly. "Wow, Chris," he began. "It looks like I've been gone for a while. You and Helen, huh?"

Chris smirked. "Oh, you're so sure you'll win, hmm? See, I took the bet because I'm sure I'll win. Let's go!"

Sonic shook his head, smiling. There was no reason to expect Chris to have actually accepted that bet unless Chris was truly prepared to follow through if he lost, which in all likelihood, Chris would. Chris's feelings were, of course, private, and it wasn't in Sonic's nature to pry into drama like that, but he did find it interesting. His friend was growing up.

Sonic sat himself along the top set of wings on the biplane. As soon as he was ready, Chris started the engine and began takeoff procedures. The whirring of the engine rapidly increased in frequency as the biplane shot out of the hanger, accelerating quickly to rotation speed. Soon, the two friends were soaring through the sky.

Chris explained the flight plan to Sonic. "We're first going to go ahead and do a flyover of downtown Station Square. Even though it's densely populated, the whole area isn't that small. I'm not really expecting there to be Chaos Emerald there, since downtown is where you first appeared and scattered the emeralds. It should be fairly easy to rule out. Then, we'll fly up and check selected areas north of Station Square, and then we'll move west. That should be enough ground for a day's work."

Sonic looked into the cockpit and gave a thumbs up of understanding. His hand was gripping the side of the aircraft's wings tightly, holding his balance.

"I've calibrated the Chaos emerald tracker to lock on to the energy signatures of all seven emeralds based on archival data we have from the last time you were here. If it goes right, I think I may even be able to deduce exactly what color the emerald is, since each gives off a different energy signature. It's quite fascinating, actually. Even though they are virtually indistinguishable in terms of function, they differ in color and signature in such a fundamental way. Grandpa and I were…"

Chris trailed off. Sonic had wrapped his feat around one of the pillars of the biplane and laid himself onto his back, with his hands behind his head. His eyes were closed.

"Sonic?" Chris probed tentatively.

The blue hedgehog did not respond.

Chris rolled his eyes. His best childhood friend had fallen asleep as he was explaining how his greatest invention worked. Classic.

Granted, Chris thought, most of the work on this device was done by Grandpa and Tails. I just improved their designs and worked on some of the math.

Chris looked down and observed the busy streets of Station Square. From his altitude, the cars on the streets looked like tiny ants. The humans on the sidewalk were even smaller. He banked the plane left slightly to align himself on his most optimal flight path, then sat back and relaxed a bit, letting the autopilot take over for a time.

He gazed over at Sonic, who was still napping. Chris shook his head. For many years, Chris had only been able to see Sonic in photographs and on computer screens. While he was actually in Sonic's world, he had to pinch himself every now and then and really convince himself he was actually looking at light reflected directly off the hedgehog's blue fur. This was him. This was his best childhood friend, back again!

"Hey Sonic?" said Chris.

The blue hedgehog cracked open an eye. "Hmm, Chris? Whoops, I must've fallen asleep." Sonic chuckled. "Sorry about that. I guess I'm a little tired from these past few days."

Chris smiled. "That's okay, Sonic. I figured as much. I was just wondering… I, uh, I've been meaning to ask you this for a while now, and I've never found the right time. I figure now is as good a time as I'm ever going to get."

Sonic raised an eyebrow, curious as to what Chris had to say.

Chris took a breath, paused, then said, "When you were last in this world, you gave me a choice. You told me that if I really wanted you to stay in this world, then you would stay."

"Chris…" said Sonic, turning to face his friend.

"Did you really mean that?" asked Chris. "We know now that the whole thing was a scam, but at the time, we really believed that if you didn't leave when you did, then it would have been impossible for you to go back. Did you really mean it when you said you would stay?"

Sonic said nothing. He looked away into the distance.

Chris continued, "You have friends and family back in your own world that you would be leaving behind if you had stayed in this world. These are friends you've known for way longer than me. Think about Tails, think about Amy, think about Cream, think about Knuckles. You would have been abandoning them. It wouldn't have been fair to them if you left them just to stay with me. Would you have really done that to them if I had asked you to stay?"

Once again, Sonic remained silent for a few moments. Chris shifted uncomfortably in his seat as the silence soaked in.

Finally, Sonic spoke. "I guess I just trusted that everything would turn out okay in the end. I believed that whatever decision you made would be the right one."

"You were wrong to trust me!" cried Chris. "I wanted nothing more than to ask you to stay in this world. One more second, and I would have done it! You were this close from never seeing your friends back home ever again. And all just for me, a dumb, selfish kid whom you only knew for a year. You should have never given me a choice!"

"But you didn't choose that path," said Sonic. "Even though you wanted me to stay so badly, something inside you told you not to make that decision. Why?"

Chris frowned. "So is that what it was? A test? Did you just want to see whether I was capable of making the right decision? Would you have left either way?"

Sonic turned and faced Chris, looking him directly in the eye. "No," he said. "I meant what I said. If you had asked me to stay, I would have stayed."

"But Sonic," said Chris, "why? It doesn't make sense. Wouldn't you have been sad not to see your old friends ever again?"

Sonic shook his head. "It wouldn't have been the last time."

"Huh?" said Chris.

"It wouldn't have been the last time I would see my friends if you had asked me to stay," said Sonic. "I know I would've seen them again eventually, just like how I knew I would see you again eventually. The truth is, I don't believe in goodbyes. All of the friends I've ever made in my life—I'll see them all again, sometime down the road. In the meantime, all I have to do is keep running down that road! Can't see anyone if I stay in one place the whole time. As long as I have a place to run to—I'm happy."

Chris gulped. A place to run to. This was essentially what Sonic had said the last time he was here. Chris wanted to agree with Sonic. Heck, if he were still twelve, he would have wholeheartedly believed him. But the more logical side of him, the more adult side of him, saw it as foolish optimism. How could he believe that he will see all of the friends he ever made in his life? Reluctantly, the inner realist in Chris persuaded him to ask one more question of Sonic:

"Even Cosmo?"

"Yes," said Sonic without hesitation.

"But Cosmo is—"

"I talked to her," said Sonic. "Just before you left, she spoke to me. She told me that if you ever miss her, just look to the trees and the sky… that's where she'll be."

Chris opened his mouth to reply, but nothing came out. What Sonic said was nonsense. How could they ever see Cosmo again? Cosmo was dead. She sacrificed herself to save the galaxy from the terror of the Metarex. There was no way she could have spoken to Sonic after her body was destroyed. The realistic side of Chris wanted to accuse Sonic of lying.

But another side of Chris held him back. That part of Chris did want to give Sonic at least the benefit of the doubt.

Frankly, before he arrived, Sonic's entire existence would have been considered nonsense by almost everyone on the planet. A blue, talking hedgehog who could run faster than the speed of sound? What kind of hogwash is that? Sonic's arrival had been an anomaly. While there were eventually logical explanations discovered that accounted for his arrival, humanity had to fundamentally change their view of the world in order to wrap their heads around those explanations. Humanity had to realize that they inhabited one half of a parallel set of universes. And now that Sonic had been hopping universes with Shadow, humanity now knew that their universe was just one of a possibly infinite number of universes, connected like a web.

Right now, one part of Chris thought that Sonic's optimism was complete nonsense. The other part found that nonsense persuasive.

"Promise me," said Sonic, "that you will never say goodbye."

Chris looked at Sonic quizzically. "What do you mean?"

"I hate goodbyes," said Sonic. "They're too… forever. Instead of saying goodbye, I always say, 'See ya!' What do you think, Chris? Will you promise me that you will never say goodbye? Just say, 'See ya!'"

"I… I promise," said Chris.

Sonic smiled and closed his eyes. "Thanks, Chris."

Chris smiled in turn. After a few moments, the center console of his plane gave a soft chirp.

"Oh, Sonic, we've finished our sweep of downtown Station Square, as well as the northern territories. We're going to head out west now. I'm going to turn the plane so hold on, okay?"

"Okay!" said Sonic, who stood up excitedly, gripping a pillar of the biplane for support as Chris banked the plane hard to port. The tilt of the plane made staying on top of the wing a bit more difficult, but it was nothing compared to what Sonic had already experienced. The hedgehog was clearly enjoying himself.

That is, until Chris completed his turn, changing his heading to west. Sonic's eyes gazed forward, and suddenly, color drained from his face as he beheld their destination.

"C-Chris, w-where are we going?" asked Sonic.

Chris looked to Sonic, and his eyes widened. Sonic was gripping the pillar connecting the top wing with the bottom wing with essentially all four limbs, as if he were hanging on for dear life. In the space of a few seconds, Sonic had been reduced from his usual danger-loving self to this.

"What do you mean? We're going out west," said Chris.

"A-any place in particular?" stammered Sonic.

Chris said nothing. He had a very strong suspicion as to why Sonic's behavior had changed so radically. In fact, he had predicted this to some extent, but he did not predict just how much it would affect Sonic. Chris gazed over one more time. Sonic had closed his eyes, still gripping the pillar of the biplane tightly in what was almost a fetal position.

Chris returned his gaze forward. Before them, directly west of Station Square, was a vast ocean, stretching thousands of miles west.

"I'm going to try to do a water landing," said Chris. "I've been wanting to practice this maneuver for a while now. Normal planes of this variety only land in the water in the event of an emergency, but Chuck and I have made special modifications to this aircraft that will make it amphibious. It should be able to land on both land and water!"

"Should?" replied Sonic.

"Well, I've never tried a water landing alone before," said Chris. His voice lowered. "Like I said before, I think you should come into the cockpit and sit down—just to be safe."

This was it. This was the trick he had planned in order to win the bet he made with Sonic. Would it work? Chris knew that Sonic didn't like water. When Sonic first arrived in Chris's world, he had accidentally landed in Chris's backyard swimming pool. Despite being such a skillful runner on land, Sonic's locomotion in water was practically nonexistent; he was an incredibly weak swimmer. This was actually how Chris and Sonic met: Chris had saved Sonic from drowning in the deep end of his pool.

Chris had deliberately set the flight course to fly over the ocean for a time, and he had also deliberately planned to attempt a water landing—all to try to coax Sonic to enter the cockpit.

If Chris were to win the bet, it would not be the first time that Sonic and Amy had arranged a date together. Back when Sonic and Amy were both in Chris's world, Amy had announced one day that Sonic had finally asked her out on a date. The only problem was, Sonic ended up failing to show up for the date—he had been busy investigating the whereabouts of Eggman's messenger robot Bokkun. At the time, Eggman had been imprisoned for his attempts to take over the world, and Bokkun had been plotting a jailbreak. To make matters worse, he had apparently scheduled to race Sam on the same day! Amy had been overcome with anger, but her anger subsided a bit when she learned about the jailbreak attempt, and Sonic had arranged to race Sam after his date with Amy, not concurrently.

Chris looked over to Sonic, who was still gripping the pillar tightly, but Chris noticed that he had straightened a bit. "I'm fine," said Sonic.

Chris shrugged. "All right, here goes nothing."

Chris pressed a button on his instrument panel. "Water landing gear down!" he announced.

In a show of incredible engineering, the wheels of the biplane retracted and a set of buoyant pontoons revealed themselves beneath the plane's fuselage. Slowly, he pushed the nose of the plane down and began to descend towards the water.

This triggered Sonic into action. Slowly, he turned towards the cockpit, eyeing it carefully. One false step or bad grip and he could be blown off by the strong winds into the water below.

Sonic looked down. The shoreline of Station Square was growing farther and farther away, and as far as he could see west, he could see zero land. Sonic's breathing began to grow more erratic as his panic level began to rise.

"C-C-Chris," said Sonic. "Let's go back to land."

"Do you want to come into the cockpit? Like I said, you'll be safer in here."

Sonic said nothing, but gave a barely perceptible nod. If Chris hadn't been paying close attention, he could have missed it. Chris took a hand off the yoke and reached a hand toward Sonic. "Grab onto me, Sonic," he said.

Sonic accepted Chris's hand and, in one swift movement, Chris pulled Sonic into the cockpit, where Sonic strapped into the passenger seat behind him.

"I guess this means I win the bet," said Chris, a hint of triumph in his voice.

Sonic said nothing in response. No witty remarks. No complaints. No congratulations. The hedgehog behind him was silent, and it made Chris a little worried.

The water landing itself was, as Chris predicted, trivially easy. Although it was his first time performing the maneuver alone, he had ample practice with flight instructors in other kinds of seaplanes. When the plane stopped to a rest in the water, Chris turned around to check on Sonic.

"Hey, are you okay?" asked Chris. "I know you don't like water, but we've flown over water together before, and you seem more scared of it now than back then."

Sonic's eyes were completely closed, but he nodded in agreement.

"That's not healthy," said Chris. "Do you want to talk about it?"

"We've got more important things to do," said Sonic.

"I don't know," said Chris. "I'm sure it's affecting your fighting too. What if you have to save yourself when you're near a body of water?"

"Let's just get out of this place already!" snapped Sonic.

Chris obeyed. He quickly started the plane again and took off, heading in a return direction to Station Square.

"Sorry, Sonic," he said. "It was wrong of me to take advantage of your fear of water just to win a bet. I didn't realize how big a problem this was."

"No, I'm sorry, Chris," said Sonic. "Sorry for yelling at you back there. I honestly don't know what got into me."

"It's okay, really," said Chris. "Trust me, as long as you're in this cockpit—which you will be from here on out—you'll be fine. We'll just—"

Suddenly, a loud alarm pierced through the cockpit, while Chris's center console flashed bright yellow.

"What's going on?!" cried Sonic. They were still over the ocean. "Is something wrong with the plane?"

"No," said Chris. "I think we just found the yellow Chaos emerald."

Tails had spent the entire rest of his day completing the universe-hopping device with the help of the schematics provided by Doctor Eggman. At several points, Tails found himself having a complicated sense of admiration for Eggman. The Doctor had made a few key technological breakthroughs. Tails, however, went a step further. He combined the breakthroughs that Eggman had made with his own, resulting in a device that was even better than Eggman's original design.

After some time, Amy and Cream appeared at Tails' workshop.

"Hey Tails!" greeted Amy. "Did you visit Knuckles?"

"Hi Amy! I sure did," said Tails. "Oh, and hey Cream!"

"Hi Tails!" said Cream happily. Cream had a habit of using honorifics with almost everyone she interacted with—for years, she had referred to Sonic as "Mr. Sonic". It was only recently that she finally dropped the "Mr." honorific with Sonic. For Amy and Tails, however, she had dropped the honorifics very early on. They were closer to her age, and she easily considered them her best friends, second only perhaps to Cheese.

Speaking of Cheese, the Chao was noticeably absent from Cream's presence at the moment. "Where's Cheese?" asked Tails curiously.

"He's still at home, sleeping," said Cream. "He stayed up too late at the party last night and was too tired to wake up in the morning." Cream giggled. "Silly Chao."

"What did Knuckles say?" asked Amy.

Tails relayed to her everything that happened, from Knuckles' reluctance to strain the Master Emerald to Bokkun's uninvited delivery of Eggman's message and the transportation device schematics.

"Remember, there could be a time difference between whatever universe Sonic is in and our universe—there's no way to know how much time has passed for Sonic the longer we stand here," said Tails. "Fortunately, I am pretty much done building this device! I spent all day working on it. Eggman was really smart in designing this, but I think I made a few improvements that'll make things a lot easier."

"Like what?" asked Amy.

"Eggman's original design drew residual energy from the Master Emerald, but the energy leakage was kind of severe. After just one jump to a different universe, we would need to carry the Master Emerald with us to jump back to our home universe—all the energy is used up after one go." Tails began walking to the back of his workshop. "My device, on the other hand, handles the energy a bit more efficiently, so one charge should be able to hop universes at least ten times before it needs to be recharged."

Tails stopped walking. Next to him was a device that looked like a small rocket. A door in the frame opened up to a compartment where about six human adults could fit. If they all squeezed in, maybe a few more child-sized animals could fit as well—fortunately, almost all of Sonic's friends were child-sized animals.

"Eggman's original design could pretty much only fit Chris inside it and no one else. I made my machine a little bigger," said Tails.

Amy hugged Tails, who gasped, not expecting the sudden embrace.

"Thanks, Tails," said Amy. "What would we ever do without you?"

Tails quickly returned Amy's embrace. When they separated, he rubbed the back of his head humbly. "Heh, Eggman gets a lot of the credit for this one."

Amy shuffled uncomfortably for a few seconds. "I'm sorry again about this morning." Earlier that day, she had snapped angrily at Tails for failing to prevent Sonic's disappearance. Tails didn't deserve the blame—there was clearly nothing more he could have done to prevent Shadow from causing Chaos Control.

Tails quickly accepted the apology, then turned to his machine. "I've still got a few issues left to debug," he said. "But I think it should be ready to go in two hours, give or take one."

"That's great, Tails!" said Cream.

Suddenly, an unwelcome, adult voice inserted itself into their conversation: "We're going too, of course."

The three kids turned to determine the source of the voice. It belonged to a tall, mischievously grinning man with a red jacket and a peculiar, egg-shaped body. He was followed by three humanoid robots.

"Eggman!" they all cried together.

"Who told you that you were welcome here?" said Tails.

Eggman's mischievous grin turned to one of feigned hurt. "I'm hurt by your words, Tails. I would have thought one genius would be more respectful to another."

"That's right!" said Bokkun, pointing accusingly at Tails. "Who do you think brought you the stuff you needed to build that fancy machine, huh? It was Doctor Eggman and me."

"I agree!" said Bocoe.

"You should be bowing in gratitude in the presence of the Doctor," said Decoe.

Amy gave an audible scoff.

Tails crossed his arms. "Your plans were important to getting this to work, and because of this, I suppose you can come with us. But this is just a temporary truce—it doesn't make us friends!"

"Yeah!" said Cream. "You've tried to hurt us so many times, and friends never try to hurt each other!"

"Now, now," said Eggman. "You won't have to worry about any kind of friendship. It's hard enough for me to even be here talking to you without trying to hatch some sort of diabolical scheme. But it's no fun if your annoying hedgehog friend isn't here to stop me."

"Wait," said Tails. "You actually think it's fun to have Sonic stop your plans?"

Eggman widened his eyes for a split second, then quickly regained his composure. "No!" he cried. "I misspoke."

"Aaaanyway," said Amy. "I think we need to give Tails some room to finish his project."

Eggman walked towards Tails' device and examined it with great interest. For the most part, he said nothing, but his face betrayed his admiration. There were a few instances where he stopped to ask Tails why he made a particular design or engineering choice. Tails almost always had an immediate answer, though once Eggman actually caught an error that Tails had made. Through this process, the two accidentally began to work together on the device.

After a while, Amy and Cream said they wanted to head home in order to prepare for the jump across universes, promising to return in an hour.

"I want to ask my mother and make sure she knows where I'm going," explained Cream. "I also want Cheese to come with us."

"Also, the last time we went to Chris's world, we brought nothing with us!" said Amy. "No extra clothes, no personal belongings at all. We had to start completely from scratch. We're not making the same mistake this time."

"Uh, okay," said Tails, who looked confusedly at his closet in the corner of the room. The thought of packing clothes hadn't occurred to him at all, but then again, Amy was a girl. "But remember, Amy," said Tails, "we only have so much room in here, and we're also trying to fit Eggman in as well."

Eggman's lackeys—Bocoe, Decoe, and Bokkun—snickered a bit. "It'd be a miracle if she doesn't bring her entire wardrobe," whispered Bocoe.

"What wardrobe?" said Bokkun, and they all laughed.

Amy took notice. "What's so funny, boys?" she hissed.

Immediately, the three robots shut up. Despite being made of metal, sweat inexplicably began appearing on their outer surfaces. All three were acutely aware of Amy's hot temper, having been at the receiving end of her omnipresent hammer on countless occasions.

"I want to know what you said," Amy repeated.

"W-we were just, uh, laughing about how, uh, Eggman might not fit in the capsule!" said Bokkun quickly, without thinking.

As soon as Bokkun said this, Eggman whipped around and glared at Bokkun, who raised his hands, becoming flustered. "Wait, that's not— agh!"

"Well, I think that was a very mean thing to say," said Cream, crossing her arms. "Even if it's Eggman."

Cream's chastisement caused Bokkun to blush furiously. Unable to speak any further, he quickly left the room, flying off into the setting sun.

Seeing this, Amy and Cream looked at each other for a moment, then started to laugh. They left Tails' workshop soon after. When they returned an hour later, Amy carried a suitcase, while Cream carried a small bag—Cheese the Chao also came along, flittering about Cream happily. Right behind them was a certain red echidna.

"Knuckles!" cried Tails.

"Hey Tails," greeted Knuckles. "I heard you and Eggman worked together on a machine that can hop universes."

"Yep!" said Tails. "We're almost done with it too. Time is really important—if we don't rescue Sonic as soon as possible, a lot of time could pass for him even though a short amount of time passes for us. You remember how Chris aged six years even though it was only six months for us."

Knuckles nodded. "What I'm interested in is how you're going to power the machine. You told me earlier that you needed the Master Emerald, and I thought I made it clear I wasn't comfortable using the Master Emerald to power anything at this time."

Tails smiled. "That's where I got Eggman's help. The Master Emerald inherently radiates residual energy, even without having to pray to it like you normally do. It isn't powerful enough to power the Blue Typhoon or the Sonic Power Cannon, but Eggman found an efficient way to use the residual energy to hop between universes. The Master Emerald's residual energy was how Chris was able to come to this universe; he found the signature of the Master Emerald's residual energy."

"Something doesn't make sense to me," said Amy, who had been listening in. "Why wasn't Chris able to use the same thing to come back to us? Surely he would have wanted to visit."

Tails nodded. "At the time, Chris's world and our world were the worlds that were most aligned at a quantum level. However, shortly after Chris left our world, that alignment ceased to exist. Eggman made a rather brilliant observation that allowed him to predict this before it happened, and that was how Chris got back to his world in time. This machine is an improvement on the same machine that sent Chris home, only this time, we won't be going to Chris's world, but rather, the universe that is most aligned with our world."

"But Tails," said Knuckles. "Once you enter the next universe, the Master Emerald won't be with you. How will you use its energy in the other world?"

Tails smiled. "That's the improvement we made. Whereas Eggman's original device was only able to siphon enough energy for one jump, this device should be able to siphon enough residual energy for at least ten jumps, which means we should be able to visit at least five worlds and make it back here without running out of energy. And that's just a conservative estimate too. Don't forget also that Sonic and Shadow should have all seven Chaos emeralds with them—if we find them, we can use the emeralds as extra power."

Knuckles smiled and playfully punched Tails. "I knew you'd figure something out. Great job, Tails!"

Tails blushed. "I-it's nothing, really."

"Knuckles, are you going to come with us?" asked Cream.

"No," replied the echidna. "I have to stay with the Master Emerald."

Cream frowned, and Amy was about to say something in response before Tails interrupted.

"That might be a good thing," said Tails. "If we ever get lost, and we can't find our way home, then having the Master Emerald here in this world would allow it to serve like a lighthouse—it's how Chris found his way back here a few months ago. The Chaos emeralds share an intrinsic connection with the Master Emerald, and we can exploit that connection once we have the Chaos emeralds—just like you said before, Amy!"

At this point, Eggman coughed loudly. "I hate to ruin the moment, but time is running short. With every minute that ticks by, we could be losing the better part of an hour wherever Sonic and Shadow are."

Tails nodded. "It's time to go, is everybody ready?"

Amy, Cream, and Cheese declared their assent.

"Bocoe, Decoe, where is Bokkun?" asked Eggman.

"I'm here," said a voice behind them meekly. Bokkun had returned quietly while they were talking and was now sitting on one of Tails's couches. Little did anyone except Bokkun know, however, that Bokkun had also brought another person to Tails's workshop. After getting flustered over Cream, of course Bokkun had run into the one other person in the world who knew about his crush on the rabbit, and that person had forced him to sneak her into the workshop. Presently, Rouge the Bat hid in an obscure part of the ceiling, waiting to stowaway in the capsule.

"Are you all ready?" said Eggman.

The robots said yes.

"Thank you for your help, Knuckles," said Tails.

"I didn't do anything!" Knuckles replied.

Together, the group wheeled the machine outside. The sun had set, and the half moon illuminated itself against a picturesque starry sky. It was a gorgeous night, and Tails looked at it and gulped.

What if the machine doesn't work? thought Tails. What if we get stuck in some unknown universe with nothing in it? What if this is the last time we'll see a starry sky?

Tails wrapped his two bushy tails around himself. In his head, he saw the face of Sonic. What would Sonic do in this situation? Sonic would say that everything would be all right. Sonic would say that we would figure everything out in the end. Sonic would say that this won't be the last time…

The group entered the capsule. Although the capsule was sizable, it was still a tight fit, and everyone was standing fairly shoulder-to-shoulder in the end. Rouge had surreptitiously entered as well. Since she was able to fly, she found a space in the top of the capsule to stow away in that no one could see.

Knuckles walked out of Tails' workshop and waved. "Good luck," he said. "Give Sonic my regards."

Amy and Cream waved back.

"Goodbye, Knuckles!" said Cream.

"Chao chao!" cried Cheese.

"Bye!" said Amy.

Tails smiled as he gave Knuckles a short wave. Long ago, Tails had made a promise to Sonic about times like this. It was a promise that he had always carried with him. Nothing could summarize Sonic's personality and spirit better.

Tails had promised Sonic that he would never say goodbye.

Tails cupped his hands around his mouth and shouted: "See ya, Knuckles!"