Okay, this is a big one. And it's complicated, so don't comment on it until you understand everything I've said.
Mysteries that are perfectly solved by this theory:
1: Why can Roxas use two keyblades?
2: Why do they take the form of the Oathkeeper and Oblivion?
3: Why does Xion have a Keyblade, and why is it "fake"?
4: Why does Riku have the Way to Dawn Keyblade in KH2?
5: Why could Riku snatch and use Roxas' keyblade in Deep Dive?
6: What happens to Xion in the end?
7: Why does Kairi use a Keyblade in that scene in KH2?
Here goes:
Roxas, at the time he entered the Organization, could only use the Kingdom Key. This is what he's been seen to use in 358/2 Days thus far. Xion, when she entered the scene, didn't have the ability to use a Keyblade at all at that point, according to this theory. Be getting to that later, but first of all, I'll explain how Roxas got hold of his second Keyblade, which in this case would be the Oblivion.
Roxas has the Oblivion because he obtained it from Riku. Like the Ansem Reports say, Riku lost to Roxas once before the Deep Dive fight. That's most likely when Roxas got the Oblivion. But Riku had no Keyblade, you say? Well, what about the Way to Dawn Keyblade he uses in KH2? He can easily have had that since not long after CoM, then lost it to Roxas early in Days' story. Then, he probably regained it when Roxas disappeared. But at that time, he had taken the form of Xehanort's Heartless, and was unable to use the Way to Dawn because of his Darkness. As soon as he regains his original body in KH2, he's immediately able to use the Way to Dawn again, proving he had it with him all along. Oh, and get this: It would explain why Roxas couldn't summon the Oblivion back from Riku in the Deep Dive fight: It was Riku's in the first place! As to why it changed shape from the Way to Dawn to the Oblivion... well, it's not really a problem at all. Keyblades in the KH series change shape all the time.
Furthermore, this means that most likely, the Keyblade Riku gives Kairi in KH2 is the very same Keyblade, changed shape again to reflect Kairi instead of Riku/Roxas. Since he couldn't use it himself, why not lend it to Kairi? Afterwards, he simply got it back, and that explains why it's never seen again.
All of this has been rather basic stuff though and I'm sure it has been posted before. But now it gets interesting.
Sure, the Oblivion is now explained, but what about the Oathkeeper? Did his original Keyblade take that shape just to reflect Sora's connection to Kairi(Remember, the original Oathkeeper is simply Kairi's good luck charm chained to Sora's Keyblade)? No, it didn't!
For this theory to fit, Xion must be heavily connected to Kairi. I prefer the Aqua theory or even the Zexion theory myself, but that's not what the trailers are leaning towards. So, assuming Xion is related to Kairi...
Roxas has the Oathkeeper because he fights Xion, defeats her, and obtains her keyblade. Yup, the same way he defeats Riku to get the Oblivion, which makes a lot of sense. Remember what Sephiroth once said? That he'd be the Keyblade's wielder if he defeated Sora? As did Jack Sparrow. This isn't a mechanic that has ever been brought up by major characters in the games, but it could very well be fact: When you defeat a Keyblade Master, you can possibly obtain his/her Keyblade as it sees the victor a more worthy wielder. This is thus related to how the Keyblade of KH1 kept switching sides between Sora and Riku. So, late in the story, Roxas has to fight Xion(it's bound to happen at some point anyway), and gain the Oathkeeper, and from then on you always dual-wield.
So why the heck has that Keyblade now taken the form of the Oathkeeper? Xion is seen to wield the Kingdom Key in all trailers, after all. Well, that's because all those trailers are from earlier points in the game. The Kingdom Key probably doesn't change into the Oathkeeper until this final showdown, most likely when Xion dies. This is because Xion is assumed to be some "alternate form" of Kairi, like Naminé, and when she "dies", she probably returns to Kairi. Like Riku says to her in the trailer: "Why haven't you returned to your original self?" or something like that. So when that happens, her Keyblade becomes tied to Kairi and takes the Oathkeeper form.
Now you may ask: But how come Roxas couldn't dual-wield before? Does Roxas have THREE keyblades now or what?
But you see, this is when it gets REALLY interesting. You see, this explains the mystery we've all heard, on how Xion "stole" Roxas' Keyblade. Like I said, I think Xion didn't originally have the ability to wield a Keyblade. I'm thinking that after Roxas steals Riku's Keyblade(early in the story), Xion steals the original one from Roxas(The Kingdom Key) and therefore you still only have one Keyblade... until, like I said, you defeat Xion and regain it, and by then it has changed into the Oathkeeper because of the Kairi connection.
So the Kingdom Key Xion is seen to wield in the trailers is in fact the Keyblade Roxas originally had.
This means that Xion probably defeats Roxas in a fight halfway through the story, so she can obtain this Keyblade. Or maybe it is a tie, which would be why they get one each. I'm assuming this fight will take place gameplay-wise right after Roxas' first fight against Riku, so that Roxas never gets to dual-wield until after beating BOTH Riku and Xion.
So the basic timeline is as follows:
1: Roxas joins Org. XIII with the Kingdom Key
2: Riku somehow obtains Way to Dawn, this will be dealt with in a currently untold story about Riku's journey between KH1 and KH2, as mentioned by Nomura
3: Xion joins, she has no Keyblade at the time
4: Roxas and Riku fight, Riku loses and Roxas gets the Way to Dawn, which changes into the Oblivion
5: Xion fights Roxas and steals his Kingdom Key, then defects from the Organization
6: Riku defeats Xion at Beast's Castle and calls her Kingdom Key a fake, which it kinda is
7: Much later, Roxas and Xion have a final battle which ends with Xion getting killed. The Kingdom Key has now transformed into the Oathkeeper because Xion is connected to Kairi. Expect an emotional scene here
8: Riku and Roxas fight at Memories' Skyscraper (Deep Dive). Riku snatches the Oblivion, which was originally his, and uses it to defeat Roxas
9: As seen in KH2 FM, Roxas makes a comeback, takes back the Oblivion and defeats Riku
10: Riku is forced to untie his blindfold, he changes to the form of Xehanort and defeats Roxas as seen in KH2 FM, but Roxas still has dominion over both Keyblades
11: Roxas lives in the virtual Twilight Town. At the end, he is able to summon the Oathkeeper and Oblivion against Axel, proving he still has them. He then merges with Sora
12: Riku regains the Way to Dawn when Roxas disappears, but is unable to use it in his current form
13: Riku lends Kairi the Way to Dawn, which changes shape again to one more befitting Kairi
14: Kairi gives back the Way to Dawn
15: Riku is restored to normal, and is now able to wield the Way to Dawn again
*phew*
As far as I can tell, this theory has no holes and explains a LOT. Unfortunately, it also means Xion is indeed connected to Kairi and not Aqua, much to my dismay.
Still, if anyone who's knowledgeable on Kingdom Hearts lore can find any mistakes or problems with this theory, please speak up. Don't do so unless you REALLY know what you're talking about though!
Mysteries that are perfectly solved by this theory:
1: Why can Roxas use two keyblades?
2: Why do they take the form of the Oathkeeper and Oblivion?
3: Why does Xion have a Keyblade, and why is it "fake"?
4: Why does Riku have the Way to Dawn Keyblade in KH2?
5: Why could Riku snatch and use Roxas' keyblade in Deep Dive?
6: What happens to Xion in the end?
7: Why does Kairi use a Keyblade in that scene in KH2?
Here goes:
Roxas, at the time he entered the Organization, could only use the Kingdom Key. This is what he's been seen to use in 358/2 Days thus far. Xion, when she entered the scene, didn't have the ability to use a Keyblade at all at that point, according to this theory. Be getting to that later, but first of all, I'll explain how Roxas got hold of his second Keyblade, which in this case would be the Oblivion.
Roxas has the Oblivion because he obtained it from Riku. Like the Ansem Reports say, Riku lost to Roxas once before the Deep Dive fight. That's most likely when Roxas got the Oblivion. But Riku had no Keyblade, you say? Well, what about the Way to Dawn Keyblade he uses in KH2? He can easily have had that since not long after CoM, then lost it to Roxas early in Days' story. Then, he probably regained it when Roxas disappeared. But at that time, he had taken the form of Xehanort's Heartless, and was unable to use the Way to Dawn because of his Darkness. As soon as he regains his original body in KH2, he's immediately able to use the Way to Dawn again, proving he had it with him all along. Oh, and get this: It would explain why Roxas couldn't summon the Oblivion back from Riku in the Deep Dive fight: It was Riku's in the first place! As to why it changed shape from the Way to Dawn to the Oblivion... well, it's not really a problem at all. Keyblades in the KH series change shape all the time.
Furthermore, this means that most likely, the Keyblade Riku gives Kairi in KH2 is the very same Keyblade, changed shape again to reflect Kairi instead of Riku/Roxas. Since he couldn't use it himself, why not lend it to Kairi? Afterwards, he simply got it back, and that explains why it's never seen again.
All of this has been rather basic stuff though and I'm sure it has been posted before. But now it gets interesting.
Sure, the Oblivion is now explained, but what about the Oathkeeper? Did his original Keyblade take that shape just to reflect Sora's connection to Kairi(Remember, the original Oathkeeper is simply Kairi's good luck charm chained to Sora's Keyblade)? No, it didn't!
For this theory to fit, Xion must be heavily connected to Kairi. I prefer the Aqua theory or even the Zexion theory myself, but that's not what the trailers are leaning towards. So, assuming Xion is related to Kairi...
Roxas has the Oathkeeper because he fights Xion, defeats her, and obtains her keyblade. Yup, the same way he defeats Riku to get the Oblivion, which makes a lot of sense. Remember what Sephiroth once said? That he'd be the Keyblade's wielder if he defeated Sora? As did Jack Sparrow. This isn't a mechanic that has ever been brought up by major characters in the games, but it could very well be fact: When you defeat a Keyblade Master, you can possibly obtain his/her Keyblade as it sees the victor a more worthy wielder. This is thus related to how the Keyblade of KH1 kept switching sides between Sora and Riku. So, late in the story, Roxas has to fight Xion(it's bound to happen at some point anyway), and gain the Oathkeeper, and from then on you always dual-wield.
So why the heck has that Keyblade now taken the form of the Oathkeeper? Xion is seen to wield the Kingdom Key in all trailers, after all. Well, that's because all those trailers are from earlier points in the game. The Kingdom Key probably doesn't change into the Oathkeeper until this final showdown, most likely when Xion dies. This is because Xion is assumed to be some "alternate form" of Kairi, like Naminé, and when she "dies", she probably returns to Kairi. Like Riku says to her in the trailer: "Why haven't you returned to your original self?" or something like that. So when that happens, her Keyblade becomes tied to Kairi and takes the Oathkeeper form.
Now you may ask: But how come Roxas couldn't dual-wield before? Does Roxas have THREE keyblades now or what?
But you see, this is when it gets REALLY interesting. You see, this explains the mystery we've all heard, on how Xion "stole" Roxas' Keyblade. Like I said, I think Xion didn't originally have the ability to wield a Keyblade. I'm thinking that after Roxas steals Riku's Keyblade(early in the story), Xion steals the original one from Roxas(The Kingdom Key) and therefore you still only have one Keyblade... until, like I said, you defeat Xion and regain it, and by then it has changed into the Oathkeeper because of the Kairi connection.
So the Kingdom Key Xion is seen to wield in the trailers is in fact the Keyblade Roxas originally had.
This means that Xion probably defeats Roxas in a fight halfway through the story, so she can obtain this Keyblade. Or maybe it is a tie, which would be why they get one each. I'm assuming this fight will take place gameplay-wise right after Roxas' first fight against Riku, so that Roxas never gets to dual-wield until after beating BOTH Riku and Xion.
So the basic timeline is as follows:
1: Roxas joins Org. XIII with the Kingdom Key
2: Riku somehow obtains Way to Dawn, this will be dealt with in a currently untold story about Riku's journey between KH1 and KH2, as mentioned by Nomura
3: Xion joins, she has no Keyblade at the time
4: Roxas and Riku fight, Riku loses and Roxas gets the Way to Dawn, which changes into the Oblivion
5: Xion fights Roxas and steals his Kingdom Key, then defects from the Organization
6: Riku defeats Xion at Beast's Castle and calls her Kingdom Key a fake, which it kinda is
7: Much later, Roxas and Xion have a final battle which ends with Xion getting killed. The Kingdom Key has now transformed into the Oathkeeper because Xion is connected to Kairi. Expect an emotional scene here
8: Riku and Roxas fight at Memories' Skyscraper (Deep Dive). Riku snatches the Oblivion, which was originally his, and uses it to defeat Roxas
9: As seen in KH2 FM, Roxas makes a comeback, takes back the Oblivion and defeats Riku
10: Riku is forced to untie his blindfold, he changes to the form of Xehanort and defeats Roxas as seen in KH2 FM, but Roxas still has dominion over both Keyblades
11: Roxas lives in the virtual Twilight Town. At the end, he is able to summon the Oathkeeper and Oblivion against Axel, proving he still has them. He then merges with Sora
12: Riku regains the Way to Dawn when Roxas disappears, but is unable to use it in his current form
13: Riku lends Kairi the Way to Dawn, which changes shape again to one more befitting Kairi
14: Kairi gives back the Way to Dawn
15: Riku is restored to normal, and is now able to wield the Way to Dawn again
*phew*
As far as I can tell, this theory has no holes and explains a LOT. Unfortunately, it also means Xion is indeed connected to Kairi and not Aqua, much to my dismay.
Still, if anyone who's knowledgeable on Kingdom Hearts lore can find any mistakes or problems with this theory, please speak up. Don't do so unless you REALLY know what you're talking about though!
