I’m sure everyone has thought about this matchup since Sabo snagged the Mera-Mera no Mi during Dressrosa. But does Sabo actually have a chance against the Magu-Magu no Mi Marine Fleet Admiral? Let’s give this a look.
To start with, why would Sabo want to challenge Akainu? Well, to start with Sabo is the 2nd in Command of the Revolutionary Army, a group whose main goal is to usurp the World Government. As the Marines are the World Government’s main source of military strength, it’s obvious that the Marines (headed by Akainu) would take on the Revolutionary Army when Monkey D. Dragon and his merry band of freedom fighters come knocking.
But there could be a bigger motive for Sabo to want to take on Akainu. Hint: Sabo and Ace are sworn brothers (as well as Luffy, but he’s not the main event right now), and Akainu murdered Ace. Sabo retrieved Ace’s Mera-Mera no Mi. Because simply put, Sabo wants to avenge his brother. He knew he couldn’t do it without his brother’s Devil Fruit, so he waited until he got his hands on it. Now he can learn how to use it and master it to defeat his brother’s killer.
But can he defeat Akainu? Well, let’s look at the facts as well as some knowledge of molecular structure.
Fire isn’t really a substance of its own. It’s basically plasma created by the combustion of another substance. So then how does Ace (and subsequently Sabo) turn his body to fire? Well, it’s a stretch, but this is One Piece, so I’m going for it. As we know, Logia users can turn their bodies into whatever element their particular Devil Fruit controls. But how does this work. Well, simply put, Logia Devil Fruits rearrange the user’s molecular structure by a person’s will, which is why surprise attacks are sometimes a thing for Logia users without powerful Observation Haki as the user wouldn’t be able to rearrange their molecules in time. But there is science in how the molecules change. For example, Crocodile’s Suna Suna no Mi breaks his molecules up into tiny particles of sand, and Aokiji’s Hie Hie no Mi solidifies and chills his molecules into ice.
In regard to a Logia’s power spreading into the environment, the user merely wills his or her power of molecular disruption into their surroundings, changing the landscape.
The Mera Mera no Mi is different. At the user’s will, it ‘combusts’ the user’s body (to change into the fire form) and the air (and oxygen) around the user. In addition, the more oxygen in the air, the hotter the fire will be. This is how Ace can literally transform into fire, which has no true tangibility. To reform, the user just reforms the surrounding molecules affected back into the person’s solid state.
Now this might seem pretty overpowered at first glance. But remember, the fire is reconstituted back into Ace (or Sabo) UNLESS an outside object catches on fire, in which case it will either burn or go out of its own accord. It’s like lighting a candle with another candle.
So, how did Akainu beat Ace to begin with? Well, first let’s discuss some info on Ace’s strength. It was expressed in chapter 159 of the manga that Luffy is surprised that Ace had eaten the Mera Mera no Mi, and it is explicitly stated in episode 95 that Ace hadn’t eaten the DF long before their encounter at Alabasta, meaning that Ace hadn’t actually gained full control over the DF just yet. By that notion, we can assume that he hadn’t experienced the Fruit’s Awakening yet.
On the other hand we have Akainu, who (despite immense control over his Magu Magu no Mi) likely hasn’t Awakened his Devil Fruit, either. But what does that mean for the comparison in strength?
Ace’s control over his Devil Fruit extended to orange and yellow flames, as we saw throughout the entire first saga of the One Piece anime. Now, the flames Ace controlled were likely in the ballpark of about 1,100-1,200 degrees Celsius (or an average of 2,100 degrees Fahrenheit). On the other hand, Akainu’s magma is likely around 1,300 degrees Celsius (2,400 degrees Fahrenheit), which is quite a bit hotter than Ace’s flames. But there is one important thing to consider alongside this: Unlike fire, magma retains a sphysical form. This is a free flowing substance that is hot enough to burn other objects. This ultimately explains how Akainu was able to connect with Ace’s physical form. Ace was unable to burn his molecules in time to keep an outside force from burning him, and burning him hotter than he already burned. So, in a way, Oda is correct about magma being ‘of a higher order’ than orange fire.
So, then, how does Sabo have a chance?
Well, it’s already been shown that Sabo possesses a great level of control over the Mera Mera no Mi, using it to copy Ace’s Hiken ability in episode 678. In addition, Sabo was able to coat his weapon in flames before engaging Fujitora later on in Dressrosa. This tells me Sabo has a natural knack for the Devil Fruit.
Sabo awakening his new Devil Fruit has been hypothesized to be when he focuses his mental willpower, as Logias require willpower to force the body and surrounding molecules to transform. But on the scientific end, Sabo would need to combust a lot more air (and subsequently the oxygen in the air) than Ace ever did. When he does this, the flames he generates could become blue. Blue fire is much hotter than orange, burning at around 1,500 degrees Celsius, or 2,700 degrees Fahrenheit on average.
Sabo would burn so hot that Akainu (in comparison) wouldn’t be able to burn him. Yet, Sabo could burn Akainu, seeing as magma is a physical mass and Sabo would burn hotter than Akainu’s magma. In addition, Sabo has access to Haki and was shown using it during Dressrosa. With Haki on his side plus Sabo’s blue fire, he’d easily be a match for Akainu.
*Theory by Tatsu D. John