Everybody gets off of Tonky as they reach the castle entrance. Kirito looks to Yui and see's her looking down.
Kirito: Is everything alright sweetheart?
Yui: This is just my hypothesis, but Alfheim Online is a lot different from all of the other MMO's from the Seed in one way. The Cardinal System that governs its operation hasn't been stripped down. It has the full specs and source code from the original Sword Art Online.
Sonic: Full specs?
Yui: The original Cardinal System had the ability to automatically generate quests. It gathers legends and lore from all over the world through its networks. And by synthesizing terms and story patterns from them, it can generate any number of quests.
Tails: Does that mean the one we're in was created by Cardinal?
Yui: I believe that might be the case because of how that NPC was behaved. Depending on how the source material is involved, it might run its course all the way to the very end. The data archives says that this quest and ALO itself are based on Norse Mythology which describes a final war that ends everything. Not only do the frost giants from Nibelheim invade Jotunheimr, but flame giants from Muspelheim, which is a world even lower, plan to burn the World Tree in its entirety.
Knuckles: You're kidding, right?
Leafa: Ragnarok, the Twilight of the Gods. That's impossible. There's no way a game would destroy its own maps and environment!
Tails: The original Cardinal System had the permissions to do that.
Yui: Yes, after all, the original Cardinal System's last task was to destroy Aincrad.
Silica: No way.
Lisbeth: But what about my shop?
Klein: I haven't even found my soul mate yet.
Sinon: Even if Ragnarok happens before our eyes, wouldn't the system use a backup to restore things to normal?
Yui: No, the data inside Cardinal's automatic backups only allows it to roll back player data, but not field data.
Klein: Oh, I got it.
Klein opens up his holo-window.
Klein: On second thought, nevermind.
Mighty: What were you trying to do?
Klein: I was trying to contact a GM to see if they knew about this but it's not their support hours yet.
Kirito: It is Sunday morning and almost the New Year's, after all.
Sonic: That means it's all on us now.
Leafa: Kazuto, there's not much time left.
Kirito: Alright. Let's hurry and finish this and save our home.
Everyone: Yeah!
Dr. Robotnik's Voice: Come on forward Sonic.
Leafa: Who's there?
Sonic: Dr. Robotnik?!
Dr. Robotnik's Voice: You might want to hurry if you want to save this world. Hohohohoho!
Tails: Why is Robotnik involved in this?
Sonic: We'll worry about him in a little while. Let's go!
They head inside. They fight against Golden and Black Minotaurus after they beat Cyclops. Sinon tries to shoot an arrow at Black Minotaurus but the Golden one grabs the arrow with his hand and crushes it. The Black one heals both himself and the golden one.
Sonic: Honestly I hate bosses that can heal themselves.
Leafa: This is bad. The yellow one's physical defenses are too high!
Klein: Too bad we don't have a mage that can hit it with magic.
Lisbeth: Oh great. Do you of all people say that? The black one with high magic resistance would just absorb it anyway.
The golden minotaurus gets ready for a shockwave attack.
Yui: Shockwave attack coming in three seconds!
Mighty: Not for long!
Mighty uses his spindash at the yellow one to stop the attack.
Leafa: 70 percent of the medal has faded! If we die here, we'll run out of time!
Kirito: Let's try using magic type sword skills. It might effect the yellow one. We have to try this and overwhelm it with our sword skills.
Klein: Good idea.
Kirito, Leafa, Lisbeth, Silica, Sinon, and Klein get ready to use their sword skills against the gold minotaurus. Sonic, Tails, Knuckles, Mighty, and Ray get ready to unleash their attacks.
Kirito: Silica, bubble breath, now!
Silica: Pina, bubble breath!
Pina uses her bubble breath against the gold minotaurus.
Kirito: Go!
Everybody charges in to attack. Sonic, Tails, Mighty, and Ray use their spindash, Knuckles punches six times, Leafa uses a wind sword skill, Klein uses a fire one, Lisbeth uses lightning, Silica does a water skill, and Sinon shoots an ice arrow. Kirito uses three sword skills, one fire one, one ice, and another fire skill, using his dual blades, he uses one sword skill with one sword, and another sword skill with the other sword.
Mighty: What was that?
Sonic: I don't know but let's keep going?
Everybody continues to attack. After Kirito used Rage Spike, the enemies HP goes down to the red. Asuna comes in and uses Neutron, and then Sonic uses his homing attack. The Black Minotaurus prepares to attack them and suddenly, the gold one disappears.
Klein: Sorry for your loss, buddy.
Everybody attacks the black minotaurus and takes him down. He disappears.
Sonic: That's another one down!
Tails: Yes! Two more left!
Klein: Hey Kirito, what was that move just now?
Kirito: Do I really have to tell?
Klein: Of course you do! I've never seen anything like it!
Kirito: It's a non-system skill. It's Skill Connect.
Klein: Skill Connect?
Kirito: You know how sword skills got added in ALO in the last update? But they didn't add unique skills like dual wielding, or the divine blade.
Klein: Weren't you using two swords just now?
Kirito: I was but it wasn't the dual wielding skill. All I was doing was alternating between one-handed sword skills. You can chain three or four of them in a row without any lag, but only if you're lucky enough.
Lisbeth and Silica: Woah.
Asuna: Oh boy.
Yui: What is it Mommy?
Asuna: I'm just getting some deja vu.
Flashback from SAO, after the Gleam Eyes was defeated.
Klein: Oh, Kirito, what was that move you did?
Kirito: Do I really have to tell?
Klein: Of course! I've never seen anything like it!
Knuckles: Are you sure it's a good idea to ask about skills?
Kirito: It's fine. I trust you guys. It's an extra skill, dual wielding.
Back to the present.
Tails: I think I'm getting the same vibe too.
Klein: And Sonic, when you and Asuna were finishing that boss, were you spindashing in mid-air?
Sonic: Oh. Actually that was an ability that I've learned from my future self. It's a homing attack.
Klein: Homing attack? As in an attack that lets you hit enemies when in mid-air?
Sonic: Yeah, pretty much. Anyway, we gotta run now.
Kirito: How much time is left, Leafa?
Leafa: Looks like an hour.
Sonic: An hour? We got plenty of time. This place just has four floors, right?
Yui: Yeah. The third floor is just seventy percent the size of the second, and the fourth one is a boss room.
Sonic: Perfect! We got this, right?
Lisbeth: You're always positive, huh?
Tails: It's Sonic after all.
Silica: Why is he so cool?
Kirito: Well then, let's head down to the third floor.
Everyone: Right!
They head down to the third floor and take on Centipede-like Giant. The enemy is just about to be defeated. Silica takes out its last leg with her dagger, and Tails finishes him off with a tail whip. The enemy disappears.
Sonic: Awesome job Tails! You too Silica!
Silica: Thanks.
Tails: It's nothing.
Kirito: All that's left is the boss room on the fourth floor.
They head down the corridor in the fourth floor, and they find a woman behind some ice bars.
Sonic: Looks like she got held captive here here. You alright?
Klein: WOAH!
Ray: Uh, Klein? You ok?
Woman in the Cage: Please, help me.
Klein walks up to her like a zombie. Kirito grabs him by the back of his scarf.
Kirito: It's a trap.
Lisbeth: I'm sure of it.
Sinon: It's definitely a trap.
Klein: Are you sure it's a trap?
Mighty: What do you think, Yui?
Yui: She's an NPC. She is connected to the language engine module just like Urdr was. But unlike her, she has an HP bar.
Kirito: Do you think we have to fight her?
Tails: Maybe that's not it.
Asuna: Trap or not, we don't have time to waste. We have to beat Thrymr now.
Klein: Even if it is a trap, I can't just leave her there! Even if it causes us to fail the quest, and if Arun is destroyed, I still have to help her!
Sonic: Klein's right. It's not like us to just leave someone locked up like that.
Mighty: I agree too.
Kirito: You're right. Let's help her out.
Klein: I got this.
Klein uses his katana to slice up the ice bars and save the woman trapped.
NPC Woman: Thank you, fairy swordsman.
Klein: It's my pleasure. Can you stand? Are you hurt?
Knuckles: Oh brother.
Kirito: I know right?
NPC Woman: I am fine.
Klein: Getting out of here might be tricky. Are you sure you can manage?
NPC Woman: I must first retrieve my family's treasure which was stolen by Thrym, the King of the Giants. Can you please take me there?
Klein: Of course you can. We are gonna beat that Thrym and stop this war once and for all.
NPC Woman: Thank you, mister swordsman.
She hugs Klein.
Klein: I think I'm in love.
Kirito: Don't do anything inappropriate. Especially in front of Yui.
A display window appears saying that the NPC wishes to join Kirito's party. Kirito pushes accept and the name Freyja appears.
Klein: My name is Klein. Nice to meet you.
Freyja: I'm Freyja.
Mighty: Thrym must be a lot stronger than all of the other ones we have faced. Why is Robotnik involved in this?
Sonic: Guess that's his gig. Somehow getting involved in random situations that we are dealing with. He has to slow us down, obviously.
Kirito: When we fight Thrym, we should stay at defense until we figure out his attack pattern. Then on my signal we attack.
Tails: The enemies attack patterns will change when his health goes down to yellow, and then when it goes down to red. Let's be careful out there.
Knuckles: Let's give it everything we got!
Everyone: Right!
They all head down the stairs to the last boss room. The door opens and Asuna fills everyone with buff spells. Freyja casts a spell and everyone's max health increases.
Silica: A spell that raises your maximum health?
Ray: I've never seen anything like that before.
Sonic: Let's go everyone!
They all head inside and notice a bunch of treasure.
Lisbeth: Woah. Cha ching.
Klein: We're rich baby!
Tails: This must be Freyja's treasure.
Thrym: Is that a fly I hear? I can hear its incessant buzzing. I think it's time to swat these flies before they spoil the halls.
Dr. Robotnik: You're right about that, Thrym!
Thrym walks up to them. He appears to be a giant man. Then Metal Sonic appears next to him. Good thing he's not at his height.
Lisbeth: Is that a robot?
Silica: It looks just like Sonic.
Tails: It's Metal Sonic. He was built to match Sonic's abilities. Including his speed. He has some other abilities as well.
Thrym: So Urdr has sent these bugs from Alfheim and these puny heroes all the way to my domain? I'll offer you this. Tell me where she is and I'll give you all the gold in this room.
Klein: No way we're just gonna tell you!
Dr. Robotnik: Oh well. We were actually going to crush you guys anyway.
Sonic: So what is it now, Robotnik? Up to your evil schemes as always? I'm still gonna win anyway.
Dr. Robotnik: Pretty soon you will be crushed by Thrym.
Sonic: So what? I can still outrun him!
Dr. Robotnik: Then I'll deal with you then!
Thrym: Is that Lady Freyja? Since you have left your cage, have you decided to become my wife?
Klein: Wife?!
Thrym: Yes. On the night before our wedding, I caught her sneaking around my treasure vault. I locked her up in a cage of ice as punishment.
Leafa: Hey Kazuto. I think I've read about something like this in the Norse books. It was something about Thrym and Freyja, stolen treasure, and uh...
Freyja: I refuse to marry you! Together with these brave warriors, I will defeat you and your new friend, and I will recover what's mine!
Thrym: It's no wonder why the legends of your beauty and bravery are known in every corner of the world. Well, the noble the flower, the more fun it is to pick up. After we crush these flies, I'll shower you with my full attention.
Dr. Robotnik: And after we crush Sonic and his friends. I'll have my fun taking over this world. Hohohohoho!
Klein: I'm not letting you get your hands on Freyja!
Sonic: Beating us won't be so easy!
Dr. Robotnik: You won't have to wait long to find out!
Thrym: To commemorate this day when all of Jotunheimr becomes mine, I will crush every last one of you!
Dr. Robotnik: The fight begins now!
Metal Sonic charges at Sonic, making him drop the four chaos emeralds he has.
Sonic: Oh no!
Dr. Robotnik: Hohohohoho! This time I got them all!
Robotnik holds the last three emeralds and he throws them at Metal Sonic.
Leafa: This doesn't seem good.
Metal Sonic uses the seven chaos emeralds to become super.
Kirito: Everyone! Be careful!
Thrym unleashes a punch, and Metal Sonic charges at Sonic really fast. The last fight begins.