Very nice theory. Blackbeard is easily one of my favorite characters. I know he is a villain (and not really nice) but he has such a sweet theme. His passion for dreams, fate and power. He really cares for his (main) crewmembers (see fight with Ace) and respects his enemies (WB, Luffy).
Shanks on the other hand is in my eyes a bit boring. Stereotypical good guy. And while he is fun, also a bit blank. A plot twist like this would make him far more interesting.
he wants the d!
anyway,nice theory 
This theory brings up some interesting food for thought. It may have some plot holes, but I believe as a whole it could hold some weight.
Whether or not Teach, and Shanks were friends is debatable.
It is clear that Teach knows about the will of D, and the only likely source where he could've learned about the will of D would've been from either Shanks, or Whitebeard. Since Shanks told WB that he didn't know Teach's true strength at their meeting, it's quite possible Whitebeard ignored Teach as the heir of D and invested in Ace, while Shanks took a risk on Teach. The carelessness of WB assuming Teach had no ambition, and allowed him to assume a fodder position on his ship, and Shanks revealing the true nature of D probably lead to current day events.
This theory is so plausible it's not even funny. Great job, OP.
That said, one added layer of depth to it is Whitebeard's knowledge of the Will of D. This could branch off into multiple possibilities:
Whitebeard underestimating Teach could very well be related to his knowledge about the Will of D. When he said, "The man Roger is waiting for…is not you, Teach, at the very least" may have motivated him not to chase after Teach, as well as laughing at Shanks.
Perhaps this is meant to serve as an example of why someone learning of the history out of context could be a very harmful thing, as Rayleigh suggested to Robin on Sabaody (ten points to Rayleigh; ten points taken from Roger on that one...lol). Shanks treated him like the threat that he is, and acted accordingly; Whitebeard didn't, and lost two commanders and his life as a result.
BB was never a threat to Whitebeard, judging by the fact a near dead WB whooped his ass and made him beg for his life on Marineford.
my take on the whole story is, that both men, whitebeard and shanks know about the will of d and both did bet on different horses.
for shanks luffy is the "chosen one", for whitebeard ace was the "chosen one"
At first I just read this theory and was like "lol, could be." but I didn't think much more about it and didn't really bother reading the rest of the thread.
But the past two days or so I started thinking about it more, and eventually I grew to love the theory a lot. Almost just as much as Ashura's "Inherited Will" theory.
I would love this to be true, it would explain a lot (also why Blackbeard has so much faith in himself and how he made his plan. He is too sure of himself to just be a moron who relies too much on faith. No, he must really think he is destined to do it, and Shanks telling him everything fits perfectly with that) and it would add a good touch to the story.
As I said I hope this will be true, or at least for the great part of it. It almost must be!
I could very well imagine this theory coming true, that Blackbeard and Shanks have an older relationship. Even Whitebeard pointed out that among rivals, friendships emerge. And Blackbeard's greatest "evil" is his ability for outright betrayal, both on WB's crew AND as a Government Warlord. If Shank was serious when he said "I didn't get this from being careless" means that Blackbeard is a really gnarly opponent, and has a will that's driving him to these actions.
Blackbeard has totally positioned himself in the series as the "Anti-Strawhat", they both want to be Pirate King, but they're methods and believes are completely opposite. Even Whitebeard admitted before he died that Teach "wasn't the one" probably because of the way he has no loyalty for his crew or friends. Something that all the top pirates (Roger, Luffy, Shanks, WB) value very highly.I also think that when Shanks and Blackbeard have they're stand off, I don't think Shanks is going to escape alive. Shanks is has been here this whole time to hold the line of the Pirate King for the person most worthy. It's a very cool theory, Kirk.
Well said… The recurring motif of Blackbeard betraying those around to him could have played a role in Shanks and Blackbeard's past.
Hi Kirk. I found your theory very interesting and wanted to add to some key points in your arguments, and as such have sequenced them rather out of order for ease of reading.
@Kirk:
I find it suspicious how Shanks was implicated into the whole Ace and Teach fight. We know that Rayleigh knows about the void century, the will of D, he knows everything. It is the same for Shanks, problably, since he was in Roger's crew as well.
Going with this, I believe that Shanks try to find "that man" that Crocus, and Whitebeard were talking about. Of course we know it's Luffy, but Shanks as a character, I think his duty is to find that man, and he kinda did it with Luffy and the whole bet about the new generation.
I think you hit the hammer on the head of Shanks being the first selected person to carry on Roger's will, with 'finding that man', the man who will reach Raftel and find One Piece.
During the time that he met Luffy as a kid, he was already sporting the scar, which meant that the confrontation with Blackbeard had happened since. Going by what you said; I agree with your theory that it was his duty to find 'the man' that Roger was waiting for. Who is that man though? Well, it's obviously Luffy at this point, but what attributes or qualities did Shanks see in common with the two that caused them both to be of such interest to him?
I believe that only the 'ability to hear all things' will be the necessary key to **finding/b] Raftel, but we know that the story doesn't stop there. Luffy, upon learning the True History and likely activating the weapons, will make his move along with all his allies against the WG; something Roger never managed to do. However, judging from your theory of Shank's true duty, he likely also needs a D as the Will of D has been both mysterious and instrumental throughout OP. So he'd be looking for someone who can 'hear all things' and bears the initial of D. I'd like to take the time to add my thoughts to the story below.
@Kirk:
I think that longtime ago, after Roger's death, Shanks met Teach and have seen in him the man that was awaited by Roger and co. Teach is a D, and Shanks could have been interested by him just like he was with Luffy. Shanks made a mistake and picked the wrong guy, that's my guess. Why is Teach so confident about his fate? What does he know about the D? I think he knows almost everthing, thanx to Shanks. And that's why Shanks might be so concerned by Teach. He was still young, and he made a mistake. He told him everything. Learning from his mistakes, he then did the opposite with Luffy, telling him nothing but just giving him hope and motives.
Blackbeard seems to trust fate a little too much, especially in very dire situations, and that kind of behavior is reflective upon someone who likely already knows what is to happen; that is to say, your theory of him being a failed candidate of Shank's knowledge, trusting in his destiny far too much.
We still don't know a lot about Blackbeard. What if he also, like Luffy, has the ability to hear all things? What if Shanks recognized the initial D (which wasn't unheard of) but also saw the much more rarer ability in Blackbeard and acted hastily? Per Roger's instructions and criteria, Blackbeard meets them; however, his personality is such that he is hell-bent and obsessed on world domination with this knowledge (a stark contrast to Luffy's ambition) after obtaining it. After all, telling the wrong kind of person that they're "The One" figuratively, as you said, would make him corrupted.
Continuing your theorycraft of what Shanks may have been thinking: He meets Blackbeard, recognizes his potential and decides that to fulfill Roger's will, this man needs information to do it and do it possibly fast. However, things don't work out yet Shanks won't stop Blackbeard even though he could likely wipe the floor with him (I'll touch back on this later). Years later, he meets Luffy, who also happens to be a D.
The comparison between Blackbeard and Luffy is quite common, and from the get-go they are clear contrasts down to the wire. This also meets true by your reasoning; Blackbeard is the one with the knowledge, the template and the will (ability to hear all things, Will of D, knowledge of Void History and weapons), Luffy is instead simply told to 'become a great pirate' and filled with promises and hopes instead. Shanks didn't quite see the potential until Luffy says something that sparks Shanks interest.
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Both Rayleigh and Shanks, survivors of Roger's crew are aware about 'the man that Roger was looking for', which is why this conversation is of such interest. Shanks would not be saying such words on a whim, he'd be seeking out Rayleigh to tell him something big, something potentially world changing.
Perhaps he was underhandedly implying to Rayleigh that Luffy was possibly the man that Roger was looking for, which is why Rayleigh was also super keen on meeting Luffy.**
Blackbeard seems to trust fate a little too much, especially in very dire situations, and that kind of behavior is reflective upon someone who likely already knows what is to happen; that is to say, your theory of him being a failed candidate of Shank's knowledge, trusting in his destiny far too much.
Yea.
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I think the picture of him when he was a child pretty much hint that he wasn't all that happy and confident about his fate. Something happened to him before he joined the Wb pirates. Something that changed him completely. And it's probably related about his fate.
The comparison between Blackbeard and Luffy is quite common, and from the get-go they are clear contrasts down to the wire. This also meets true by your reasoning; Blackbeard is the one with the knowledge, the template and the will (ability to hear all things, Will of D, knowledge of Void History and weapons), Luffy is instead simply told to 'become a great pirate' and filled with promises and hopes instead. Shanks didn't quite see the potential until Luffy says something that sparks Shanks interest.
! http://i66.photobucket.com/albums/h271/dark1365/shanks_zps514bc7f3.jpg
Both Rayleigh and Shanks, survivors of Roger's crew are aware about 'the man that Roger was looking for', which is why this conversation is of such interest. Shanks would not be saying such words on a whim, he'd be seeking out Rayleigh to tell him something big, something potentially world changing.
About this line, I find this really interesting. Oda hasn't hinted anything about this line, right? It can't be "I'm going to become the Pirate king" since the PK's title didn't exist back in the days. I think it's there:
http://www.mangahere.com/manga/one_piece/v58/c585/12.html
One could say that Luffy is just expressing his dream to become the PK as usual. But I would bet it's something else. Notice Ace and Sabo's reactions to Luffy's line. Sabo is laughing and Ace is shocked. It does not seem appropriate to me, if Luffy said "I will become the PK". I think it was something funny and huge, and it could be the line that Roger once said, the line that Shanks was referring to. And we don't know Roger's dream. Luffy and Roger could share the same dream. Something funny and huge. Which would mean that we still don't know the real meaning of Luffy's dream and I can totally see a twist about this. Something that only Oda could come up with.
While I think that Shanks knows about Luffy being "that man", I don't think Dragon's line was about Luffy, but the whole D's people or even the whole world… "the world awaits our answer". Heh, actually Dragon's lines are quite a mystery. As for WB, I think he realized it as well.
Sorry took me hella long to respond.
While I think the whole D and world as a whole is the main reason Dragon became a revolutionary, I believe think that line isn't meant for them but for Luffy since he said "live according to your believes Luffy" after he saw his bounty after the EL incident, he hasn't meet Luffy yet because he must be waiting for Luffy to grow up mentally and learn more about the world he is living and what he needs to do to make a change for his era but we got Robin who is capable enough to talk to Luffy about all of this stuff but Oda is keeping her quiet.
All of this is just Opinions not facts
Yea.
One could say that Luffy is just expressing his dream to become the PK as usual. But I would bet it's something else. Notice Ace and Sabo's reactions to Luffy's line. Sabo is laughing and Ace is shocked. It does not seem appropriate to me, if Luffy said "I will become the PK". I think it was something funny and huge, and it could be the line that Roger once said, the line that Shanks was referring to. And we don't know Roger's dream. Luffy and Roger could share the same dream. Something funny and huge. Which would mean that we still don't know the real meaning of Luffy's dream and I can totally see a twist about this. Something that only Oda could come up with.
I always thought that Ace's and Sabo's reactions were appropriate, because they just thought of Luffy as their weak, crybaby younger brother. But I also think you have a point, because there's no real reason to leave out that one sentence. The one other time I remember this happening is when Iva asks Luffy if Ace is also Dragon's son and Luffy replies, but the reply is not actually written. Maybe that means that there was something weird going on with Ace's parentage, maybe something that relates to the will of D.
I think that this could be significant because if the will of D. was just a middle initial everyone would have it. There might be something special about Ace/Luffy/Teach's parentage that gives them the will of D.
This video really helps to make you think about this theory, which I think is pretty well thought out 
