The world had gone pretty much mad the day that Shadow was turned into a... whatever he was. Sonic's name for it was 'a great big hunk-a-junk'. (If Shadow had really been able to answer, then he'd probably have asked what the implied meaning was, and Sonic's answer would have been a smirk and a shrug.)
The other guys, the ones in the new world Sonic had entered through the dimensional portal in theirs, all had a different name for it. Assist Trophy. Whatever that meant. All Sonic knew was that slapping a glass life-support system of Tails' onto Shadow had seemed to do the trick.
So, for every fight, Shadow could come out and help them for exactly five seconds, by using his powers to stop time.
Sonic didn't mind this. Shadow's powers were usually necessary. Yes, the blue hedgehog could run at the speed of sound, but he was never that fast when he was concentrating on what he was doing (he was several kilometers-per-hour short of that). With Chaos Control, Sonic received some extra assistance. Those weird creatures that rose from the purple gunk didn't know what hit them.
Of course, none of that helped the fact that Shadow was now made of some kind of superstrong metal and couldn't live for longer than ten minutes without a big glass case. After travelling a while, looking for the ones that had caused this whole mess - the small round Batman/Zorro cross and the one with the zigzag across his face - Sonic started to lose that previously infectious grin of his.
Shadow was stuck, and he was unable to fix anything. Although, he did have a hunch that the weird cannon the zigzag guy used on Shadow could fix things. Surely there was a reverse switch for these kinds of things, right? Sonic could just pinch it back as soon as he found the guy and change Shadow back to his regular Mobian self.
His regular mopey self. Even if Shadow had gotten over his horrible past, he still had a few negatives about his personality. There was always the relapse when they saw a cute blonde human on the street somewhere. And then the hurried breathing whenever the words 'cloning', 'stasis', 'androids' and such were thrown around. God, they had to stop watching A-I. Who cared if it was a good movie?
Sonic still wanted Shadow back, though. The guy was wandering the strange new world alone and lost. He had no clue where he was, and he'd suggested that Tails, Knuckles and everybody stay at home in case anything happened back there. It would be a disaster if what happened to Shadow happened to the rest of the people on those two planets. If even the Ultimate Lifeform got hit so easily...
It was Sonic's fault, though.
How was it his fault? Easy. The cannon had been pointed at him. Shadow jumped in the way at the last millisecond. And now he was like this.
Maybe that was it. Sonic would get Shadow out of this sitch as thanks for stopping him from suffering that fate. It was a simple "you did this, I'll do that and we'll call it even" thing. Pretty similar to what they'd been doing ever since they'd met. Yes, they could equate the ARK affair as one of those things too. So the exchange had been more of a "I turn you around, you help me defeat a giant lizard on the bottom of a falling space station and we'll call it even" thing. It was still in the main category.
And then the locals.
Sonic had originally thought that, when he'd found some locals, he'd be okay for the rest of the trip. Well, he'd found some locals, alright. Some weird bunch they turned out to be. The small guy, Mario, was somebody Sonic knew quite closely. Mario had always taken trips to Sonic's world in the past. The two were good buddies. But then there was an angel boy with a magic bow, a pink puffball, some kind of dinosaur thing and a blond elf kid with a fairy hovering around his head.
And their heads were all odd sizes, too. Sonic had been freaked out by the difference in head size for Mobians and humans, but the difference was even crazier in this world. Mario's head was about the same size as Sonic's, just a little smaller, but the elf kid and angel both had much smaller heads. The dinosaur's skull must have weighed a ton, and the puffball's head was his body, which freaked Sonic out a bit.
But that wasn't all. They all seemed to come from different universes, themselves. None of them operated on the same level. Everybody had freaky powers and strengths. Which meant that Sonic fit right in with this crowd. That was one of the oddest feelings, but Sonic really felt that he had a family as soon as he walked in. He bet that Shadow would feel just as good here too. Maybe... maybe they shouldn't leave.
But no, they had to go back. As good as it felt here, there were two planets back home, both waiting for them, and all their friends there too. There was Amy and Rouge and Cream back there, and Tails, Knuckles and the Chaotix. Of course, the Babylon Rogues would be waiting for a few rematches too. Sonic and Shadow had made that promise at the end of their last meeting, so both had to go home at some point just to follow that up.
And so Sonic pressed onwards, carrying the Assist Trophy in a mini-capsule within his backpack. Along with his camera, taking pictures of all the things he saw there. And what a lot of things to see! He'd journeyed through everything possible to get where he was right now, near the end of the world in Subspace. Those wicked new SoapShoes on his feet had walked at least a thousand miles by now.
Yeah, this world was mad, but Sonic liked it a lot.