The chapters are out of order, I'm just posting them as the are written on the Soul Kingdom Wiki.
(Shortly after Sonic is pulled out of the rubble and team leaves in pursuit of Lyric)
...
...
(Shadow suddenly appears, looking over the platform)
Shadow: There's some kind of... trace of the Crystals' energy...
(Shadow sees the boulders shake)
Shadow: Huh? Who's under there?
(rubble continues shaking, Shadow sighs before moving down to the platform to help by pulling the rubble off)
Shadow: (backs away in shock) But... how is that possible...?!
(Something... or someONE is seen coming out of the rubble)
Shadow: (He looks at the figure with shock) This... This can't be possible...! There's no way!
(hedgehog silhouette rubs his head and groans)
?: Wh-where am I... Wh-what happened...?
Shadow: But I just saw you go with...! Who are you?
?: Back at you. Who are you?
Shadow: I asked, first! Don't play around!
?: I... I... Who am I?
Shadow: Stop kidding around and tell me who you are already!
?: I... I'm telling you... I don't know who I am!
Shadow: ...Wait. Are you serious about this?
?: Yeah. The last thing I remember was coming out that rubble, but other than that... Agh! I can't remember anything!
Shadow: Great. I'm dealing with an amnesiac.
?: I'm sorry to be... wasting your time, then. I'll get going... as soon as I get my foot unstuck. (moves a boulder over off his foot, he attempts to stand up, but he cringes from putting force on himself)
Shadow: Looks like you're more hurt than I thought.
?: N-no, I'll be okay. Just a spranged ankle. I don't to waste your time. I'll be leaving now... (attempts to walk, but Shadow watches as he struggles)
Shadow: (groans, looks away for a second) I have no choice... (looks back at the hedgehog) Hold on. I'm not giving you a choice in this. You're coming with me.
?: (turns and looks confused) What?
Shadow: Look. I know it's just a sprained ankle, but I can't let go walking off on your own.
?: No, no, I'll be fine on my own. Really!
Shadow: As I said before, I'm not giving you a choice. You're definitely coming with me. Besides, you don't even know where you are.
?: (looks away guiltily) As long as... I'm not a pain.
Shadow: (whispers to self) This guy is rather difficult... at least not as snarky as the faker. (normal) Call me Shadow, to answer your question. We'll come up with something for you. Now hold on tight.
?: Huh? (suddenly picked up bridal by Shadow) Whoa! (Shadow jumps out of the pit and away)
Some time later...
Tails: What do you mean Sonic was in town a moment ago?
Cliff: We saw him. Though, I will admit that his blue was... much lighter and not as wild.
Sonic: Lighter and more sleek fur? Doesn't sound like Metal Sonic.
Knuckles: And it obviously can't be Shadow.
Amy: So how can there be another Sonic with lighter and more sleek fur?
Cliff: Shadow? You mean the black hedgehog? Funny thing is that hedgehog was with Shadow while he was here.
Tails: Wait a second. Shadow was here?
Cliff: Yep, that's right.
Sonic: So Shadow was with that other hedgehog when he was here, huh?
Tails: I wonder why the two of them were here?
Sticks: Not to mention why that no good, spankin' black emo was with someone in the first place.
Knuckles: He is quite anti-social.
Amy: Is it really possible for Shadow to... actually have a friend?
Sonic: Shadow with a friend? That's a new thing.
Cliff: Last people saw the two was them wooshing out to the woods. And I must say, the other guy was quite quick. Almost as quick as you, Sonic.
Sonic: As quick as me? Okay, this guy I need to see. Let's head out, everyone.
Tails: We're going to go find them? They can be anywhere.
Tails: Hmm... Let's start with just asking around first. If we don't find any solid information, I've been itching to try a new gadget.
(after asking around the town)
Sticks: Urgh, all I got was that they had gotten hardware supplies and then headed to the woods.
Sonic: Hardware supplies? Shadow? That's unusual.
Tails: I got that the two got a lot of rope and some digging equipment.
Knuckles: Rope and some digging equipment? What could they be using that for?
Amy: That's not all they got. Apparently, they also got a lot of food while they were here.
Sticks: The two of them must be hungry as wolves if they have gotten that much food!
Tails: Hold on a minute. Hardware supplies... excavation things... extra food... There can be only one place on the island where you would need all of that eqiupment and supplies.
Sonic: That's it! The Hidden Meadow! You need tough survival skills in order to be there!
Amy: So that's where the two of them have gone to!
Knuckles: Wait. Why would anyone, even Shadow, want to live out there?
Tails: The only reasons I can think of are either isolation or he's keeping something secret. And I'll bet my workshop that it has something to do with this second lookalike.
Sonic: Well, we'll never know if we don't see for ourselves. Shall we get going?
Amy: Again, this is the Hidden Meadows. Shouldn't we go prepared?
Knuckles: She's right, you know.
Sonic: Alright. We'll get prepared and then we'll set off when we're ready.
Tails: Got it!
(after gathering needed materials, the quest Two Hedgehogs in a Death Trap becomes available)
(after traversing the perilous path to Hidden Meadows)
Knuckles: I don't see anyone that looks remotely like two hedgehogs here. Besides the ones with us.
Sonic: Just keep looking. Those two can be anywhere.
Tails: Got it, Sonic.
Sticks: If I were an emo and a copycat hedgehog, where would I hide around here?
Amy: (hears something) Hmm? (looks up and looks panicked) Duck!
(everyone jumps out of the way of a jar that exploded once it hits the ground)
Tails: Gum tree berry grenades?!
Sonic: I've about had enough of those!
?: Well, you shouldn't be on our terf then, faker.
Sonic: Oh... (team looks to see Shadow standing on a tall rock) So this is where you've been.
Shadow: And I see that you and your little friends are trespassing on our turf.
Sonic: Wait. "Our" turf?
Amy: He must be talking about that other hedgehog.
Tails: Then they must be... (looks up and sees another grenade) Up there! Move (Sticks jumps out of the way before it explodes)
Sonic: Defense measures? I think you're losing your touch, Shads.
Shadow: Leave now.
Sonic: Not until we see this "other" copycat of me. I swear, three is just too many.
Shadow: Tough luck. But if you're not going to leave willingly, we'll just have to kick you out.
(Boss battle finishes)
Sonic: (approaches the weakened Shadow) Okay, now that you're on your last legs, tell us about the hedgehog you've been around.
Amy: (sees another grenade) Sonic! (tackles Sonic out of the way)
Sticks: Okay, that does it! (throws boomerang at the trees, but a hand cathes it) What the?! A monkey?!
Shadow: Stupid badger! Does that look like a monkey to you?
(a blur of sky blue streaks down the tree and tackles Sonic while throwing the boomerang back at Sticks, who falls back from the force)
Knuckles: What was that?!
Shadow: More like who, echidna.
(a figure stands protectively in front of Shadow, the team backs away in shock)
Amy: Th-that's... impossible!
Knuckles: N-no way! There's just no way!
Sticks: Do my own two eyes decieve me?!
Tails: H-he... I... I-I can't believe it!
Sonic: He... He looks almost exactly...!
(camera shows a sky blue hedgehog, with evened quills, three quills out like bangs, in all looking almost like a sky blue version of Sonic)
?: Shadow said to leave. So leave.
Sonic: Who are you?
?: I will not tell you. I am just a companion of Shadow.
Tails: Companion?
Shadow: Pal. He's my pal. (regains strength to stand properly) At ease.
?: You sure?
Shadow: Positive. That hedgehog there (looks at Sonic)... might be connected to you.
Amy: What did you say?
?: If you say so... pal. (hedgehog straightens and stands next to Shadow)
Shadow: There. You get to see him after all.
Sonic: Then can you answer for us what his name is?
Shadow: (grunts) While the name is only temporary, it seemed to fit the most... This is my pal, Sicön.
Sonic: Sicön?
Sicön: Yeah. That's me.
Sonic: Woah... He really does look like me... Well, almost.
Sicön: Our appearances do actually look very similar, don't they?
Shadow: The reason for this... neither of us know.
Tails: Is, uh... he why you decided to den yourself here in this very dangerous place?
Shadow: In a matter of speaking. We both made residence here.
Sticks: The emo hedgehog and his tagalong buddy are making a voodoo shack!
Sicön: Voodoo? We don't possess that kind of power.
Knuckles: You two actually live here?
Shadow: What better place could there be where no one would think of bothering us?
Amy: That does actually make sense, if you think about it.
Tails: That's true. It would be very difficult for others to get here unless they were properly prepared.
Sonic: But for what reason would you want Zicky here to live in this death trap?
Sicön: "Zicky"?
Sonic: Sorry. Does Siccy sound better?
Sicön: Uh... Unsure.
Shadow: Who said you can go around and nickname him?
Sonic: Hey, his name is a little tough to say.
Sicön: (sigh, folds arms) If it does make it easier, I guess it'll be okay with me.
Sonic: Thank you. Now back to my question...
Shadow: To keep him secret from Eggman. What else?
Amy: Why do you need to keep Siccy a secret?
Shadow: Think about it. If Eggman heard about another hedgehog with almost the same appearance as Sonic residing on this island, what do you think he would do?
Tails: He does have a point about that. Eggman would probably tear down the entire island just looking for Siccy.
Shadow: And as you just saw, Sicön has the exact powers as Sonic here, putting him in more danger.
Sticks: I can already picture him going, (uses boomerang as a mustache) "One blue rodent destroying my robots is bad enough, but now there's two of them?!"
Tails: Yep, he'd definitely tear down the island just to destroy him.
Knuckles: Huh. But even Eggman wouldn't dare come out here. So I guess it was a good plan.
Amy: I assume that you won't tell us where you two live exactly?
Shadow: Not chancing it. And we told you enough. So scram.
Sicön: Shadow.
Shadow: (groans and facepalms) Leave us be... (gets look at Siccy's pretty demanding face) please.
(group looks surprised for a few seconds)
Sonic: Magic word was used. Let's go, everyone. (turns and starts walking away, soon followed by the others)
Knuckles: Did Shadow really say "please"?
Tails: Siccy must be quite the influence, getting Shadow to be... polite.
Amy: I'll say.
Sticks: (has a bit of a dreamy look) I gotta admit, you guys. That blue is more radiant than the sky.
Amy: Oh my gosh! Sticks has a crush! That is so adorable! Congradulations!
Sonic: Oh brother. Here we go, again.