[I see, Half Fish-Man... huh? Quite special indeed. Can you be my companion?]
[Is this... the ability to Voice of All Things? Or the ability of the Fish-Man Race? Or... the ability of the Half Fish-Man?]
Sig suddenly remembered that when he first met Shanks, Shanks had very readily accepted Sig's identity as a "Half Fish-Man" and immediately decided to recruit Sig. At that time, Sig vaguely sensed that Shanks was interested in him mainly because of his "Half Fish-Man" identity, and guessed that a certain "Half Fish-Man" had left a deep impression on him.
Furthermore, when Shanks learned that Sig could possess more than one Devil Fruit ability, he seriously wondered if it was the ability of a "Half Fish-Man"!
Sig did indeed sense at that time that Shanks least wanted was the special ability of a "Half Fish-Man".
Only now did Sig finally understand the reason, and also know who the "Half Fish-Man" he had been concerned about was—Marshall D. Teach!
This guy is actually Half Fish-Man?
Sig was quite surprised when he discovered this.
The last time I saw Teach was when Sig beat Whitebeard to a pulp. At that time, Sig had just become the "Rose Bishop" and was not yet able to analyze Blackbeard's physical condition without alerting anyone.
And now...
Sig saw it clearly!
Blackbeard vaguely sensed the "mysterious man's" gaze, but Sig didn't care. Without Whitebeard backing him up, what could Blackbeard do if he noticed him looking at him?
If he dared to ask, "What are you looking at?", Sig would dare to go up and slap him...
Shanks cares about him a lot, but... Blackbeard is almost truly a pig now, in order to "play dumb to fool others"—at least compared to Shanks. When they were young, they could fight each other on equal terms, but now Blackbeard is far from being Shanks' match.
Indeed, he must have been hiding his strength. Sig could sense that his flesh and blood contained a different power than what he displayed, but...
Even if it were to fully erupt, it would at most be equivalent to some of the lower-ranking squad leaders in the Whitebeard Pirates, not even as good as any combat officer in the Red Regiment!
For ordinary pirates, he could indeed be considered "powerful," but he was no match for Sig, and compared to his later achievements in the original work, he was just the tip of the Iceberg.
Compared to these hidden powers, Sig was more concerned about was... this guy was actually Half Fish-Man?
Furthermore, Sig has already determined his "Fish-Man half" Lineage Factor —octopus! Like Hachi, he is a rare Octopus Fish-Man!
However, because he is Half Fish-Man, Teach's appearance shows almost no Fish-Man features, but his inner self is closer to an octopus than Hachi's!
As far as Sig knows, Hachi's internal organs are the same as a human's, while Teach, like an octopus, has three hearts.
Furthermore, at the level of Lineage Factor, Teach also exhibits distinct octopus-like characteristics— the Lineage Factor discovered by Vegapunk are essentially the DNA that Sig is familiar with...
In normal humans, DNA is transcribed into RNA, and then RNA determines protein synthesis. Essentially, proteins... or rather, the mysteries of flesh and blood, are determined by Lineage Factor.
Octopuses possess a unique ability: editing RNA. Normally, RNA is entirely determined by DNA, and mutations are rare. However, after octopuses transcribe RNA, they can edit it again in a targeted manner, resulting in changes exceeding 60%.
This is not a mutation, but rather targeted editing that has adapted to the environment...
In other words, while the evolution of other organisms is entirely Record in DNA, some of the evolutionary achievements of octopuses Record in changes to their RNA.
DNA is transcribed into RNA, which is then directionally edited. The result of this editing then guides protein synthesis—in other words, the essence of his being comes not only from DNA but also from "directed editing of RNA."
Sig now suspects that Blackbeard's ability to possess two Devil Fruit ability is due to his exploitation of this characteristic!
One fruit directly affects the DNA, which is the normal "clasp" on the Lineage Factor. The ability of the other fruit, however, is Record in the "RNA editing method." That is, with this "clasp" retained, the RNA is edited again according to this "clasp" after transcription...
It's not that Blackbeard's Lineage Factor are stronger than normal people's, but rather that he has a way of influencing flesh and blood without relying on Lineage Factor!
The goal was to achieve a final synthesized flesh and blood that possessed the characteristics of both fruits, without having two layers of effects applied to the Lineage Factor.
Indeed, in the original work, Blackbeard didn't absorb the second Devil Fruit ability by eating the fruit itself...
Perhaps it was through some ability of the "Darkness Fruit" that the "shell" of the Tremor-Tremor Fruit was absorbed into its editing nerves, instead of being directly applied to the Lineage Factor?
Of course, this situation is extremely rare.
Because normal Fish-Man have a body structure that is closer to that of humans. For example, the pure Octopus Fish-Man Hachi does not have the characteristics of an octopus.
Sig is only speculating right now, and Sig even thinks that if that's the case, then Blackbeard's actions in the original work also involved an element of "gambling"!
Blackbeard himself probably couldn't guarantee that he could Record the second Devil Fruit ability in "RNA editing methods"...
In the original work, before Blackbeard intervened in the Paramount War, he told his crew that if he failed, they would disband on the spot and "divide their luggage".
Blackbeard had no reference point; after studying his own body, he felt it was "possible" and then took the gamble.
After all, Blackbeard has always been a gambler. Just like when he was in the Whitebeard Pirates, he "gambled" that he would encounter the Darkness Fruit. If he didn't, he would accept the loss and stay on Whitebeard's ship for the rest of his life as his good son.
However, upon seeing the Darkness Fruit, Blackbeard immediately made up his mind and acted decisively without any hesitation.
Absorbing a second Devil Fruit ability was also a gamble with one's life, and Blackbeard did it without hesitation—if he succeeded, he would become one of the New Generation of Four Emperors and compete for the title of One Piece; if he failed... he would simply die on the spot!
He is arguably the most "pirate-like" person in the world of One Piece, without exception.
"Another rum, with sugar and on the rocks," Sig said to the bartender again.
Throughout this, Teach pretended not to notice, however... when the second glass of rum was placed in front of Sig pushed the glass, and the rum slid down the bar and stopped in front of Blackbeard.
"This drink is on me," Sig said in a calm voice.
The others still hadn't found anything, but Teach broke out in a cold sweat. He clearly understood that the "mysterious man" already knew he had been discovered!
Dongdong: The main reason Blackbeard is associated with the "octopus" is his pirate flag—three skulls with eight bones protruding from the back, which can be interpreted as "three hearts and eight tentacles".
This conjecture is not Ben Dong's original idea. After the "Cerberus hypothesis" lost its momentum, the octopus hypothesis became one of the more common hypotheses, although there are different opinions on whether it is a "Half Fish-Man" or a "fruit".
Connecting the two Devil Fruits with the octopus's ability to edit RNA is an original (nonsense) idea of mine, but it makes sense logically, and it also avoids involving a third Devil Fruit.
However, the chances of guessing the original work correctly about RNA are extremely low, because this hypothesis has a huge flaw: the discovery of octopus editing RNA was made by scientists in 2015, which is later than the time when Blackbeard appeared in the work.
If the RNA thing was guessed correctly, it means Oda incorporated scientific discoveries and changed Blackbeard's backstory midway through the story...
However, regardless of the explanation, that's how it's interpreted in this fanfiction! This is a foreshadowing that was established from the very beginning when Shanks appeared in the book; it wasn't just something made up on the spot...