This theory will focus on the rivalry between Shanks & Blackbeard, the history of their conflict, Shanks' current mission to stop Blackbeard, and what we can expect from the conflict in the future.
Let's get in to it
The conflict between Shanks and Blackbeard began during the famed 3 day battle between Whitebeard and Roger.
It was during this time that Buggy pointed out to Shanks that Teach seemed to never sleep.
This detail is likely very important to why Shanks considers him so dangerous.
This concept of people who never sleep was actually first mentioned by Luffy, way back in chapter 134.
Luffy suggests that people from snow countries don't sleep, because if they do, then they will die.
It is difficult to predict what the true significance of this will be, but it almost certainly applies to Blackbeard.
This would connect with the idea that Blackbeard is not a 'normal human,' as mentioned by Marco during Marineford.
Next thing we know of the history between Shanks and Blackbeard is the battle in which Shanks got him scar.
The exact timeline of this event is unclear, but it seems implied that it was early on in Shanks' career. When he was somewhere between 17 & 25 years old.
Shanks was 27 when he was using Luffy's home town as a base, and this was after he had already obtained the Devil Fruit from CP9.
We can see that Shanks already had his scar from Blackbeard at this time, so it must have happened beforehand.
Interestingly, it seems that it was after this battle that both Shanks & Blackbeard began to pursue the Gomu Gomu no Mi, and the Yami Yami no Mi.
What makes this particularly interesting, is how similar the designs of the two Devil Fruits are.
Another interesting detail to consider, is that Blackbeard scarred Shanks using the Wolverine style claw weapon that he used to use.
We have not seen him use this weapon since then, but why? Did it break? Or is Blackbeard hiding something about it?
Perhaps it is not a coincidence that it was in the chapter before the meeting between Shanks & Whitebeard, that we originally learned that it was possible to infuse inanimate objects with Devil Fruits.
It is also important to remember that Shanks was not being careless when Blackbeard managed to scar him.
Shanks warns Whitebeard to recognise the danger that Blackbeard represents, knowing from first hand experience that he is not to be underestimated.
It seems that Shanks has since developed an understanding of why it is that Blackbeard does not sleep, and how it is that he is able to consume more than one Devil Fruit.
Shanks must have considerable knowledge of the complex nature of Lineage Factors / Bloodline Elements.
Back during Enies Lobby, we learned from Blueno & Lucci that it is supposed to be impossible for anyone to eat more than one Devil Fruit.
"A greedy idiot will destroy himself."
How is it that Blackbeard is an exception? It must be something to do with his Lineage Factors.
Whitebeard did not heed Shanks' warning, and effectively fell in to Blackbeard's trap entirely.
Blackbeard was able to obtain Whitebeard's Devil Fruit in addition to the Yami Yami no Mi.
Shanks was not able to prevent it himself, because he was busy fighting Kaido.
"I'll bet he has *twice* as much fun."
This is a hint that Blackbeard's ability to have more than one Devil Fruit, is directly connected to his 'abnormal' body and the fact that he never sleeps.
We can be sure that stopping Blackbeard is Shanks' highest priority, as he has tried to do throughout the story without success.
Blackbeard's ability to stay one step ahead of Shanks, a man with in depth intel on everyone, at all times, is testament to the threat he poses.
This may be why Shanks is so keen to have Marco join his crew. A desire that noticeably goes against the pattern of Shanks' crew consisting of all non-Devil Fruit fighters.
Shanks likely wants Marco on his side for he fight against Blackbeard.
If we look closer at the dialogue here, we can see another detail that correlates directly to the idea of not sleeping. "Quit dreaming."
This brings us to the fact that Devil Fruits are apparently made through the manifestation of people's dreams.
This connects directly to the notion that Blackbeard never sleeps, and it starts to make sense of how Blackbeard is able to have more than one Devil Fruit.
It also brings the subject of Lineage Factors full circle, and establishes what is most likely to happen next.
All of the details surrounding the conflict between Shanks and Blackbeard connect to the subject of Lineage Factors.
Shanks is currently hunting Blackbeard, and we've just seen one of Blackbeard's ships arriving at Egghead, home of Vegapunk.
My original theory on the answer to Blackbeard's abnormality was that he is actually the son of, and test subject of Vegapunk, who I originally predicted was Blackbeard's father.
I'm not sure about this idea now, but I still think it is a distinct possibility.
You can read that theory here, if you are interested.
A Cenotaph, from the Greek, "κενοτάφιον." Refers to an empty tomb that is erected in honour of the deceased whose remains are elsewhere or otherwise lost.
In this theory, I will focus on the Cenotaph that seems to sit in the centre of Alabasta's royal crypt.
Let's get in to it.
It seems that this empty tomb in Alabasta's royal crypt represents a parallel to the Empty Throne at Mariejois.
I believe that this cenotaph is supposed to represent the tomb of Nefertari D. Lili.
Back in chapter 1084, Cobra mentioned that Lili never made it home to Alabasta.
In this theory, I will try to convince you not only that Akainu will be the main antagonist of Elbaf arc, but also that Dragon and Kuzan will both become directly involved.
Let's get in to it.
What could possibly lead to Akainu becoming the main antagonist of the arc, and what could bring both Kuzan and Dragon into the picture as well?
Oda is distracting us with the emotion of Robin and Saul's reunion, so we're not paying attention to the broader implications.
The concept of the Sun God Nika was first introduced to us in chapter 1018, during Jinbe's fight with Who's Who.
Who's Who told us of the legend of a warrior who it is said will one day free the slaves. A Warrior of Liberation!
Although we had not heard of this before. This legend seemed familiar to us already.
This is because Oda planted the seed for it was back in Skypiea. Through this scene of Luffy and the crew dancing at a bonfire. All the way back in chapter 253.