Mera Mera no Mi

The Mera Mera no Mi is a Logia-type. Devil Fruit that allows the user to create, control, and transform into fire at will. It was eaten by Sabo, and previously Portgas D. Ace.

Appearance
The Mera Mera no Mi is a round orange fruit, composed of many flame-shaped components with swirl patterns on each one, and has a swirled stem on the top. It is small enough to be held in one hand.

Strengths
The fruit's major strength, like other Logia types, is that it allows the user to produce as well as become the element they control. In this case, the user is able to create, control, and become fire. With this in mind, the user can create devastating fire-based attacks and gain a high resistance towards most heat-based attacks. The flames can also be used to bolster the kinetic force of physical attacks. The user is also able to avoid normal physical attacks by turning into fire and allowing the attack to harmlessly pass through their fiery body. Igniting oneself also has the added effect of burning an opponent if he or she had tried to physically harm the user.

When this power clashes against certain other Logia on equal grounds, this seems to come to a stalemate: neither smoke nor ice was able to overcome nor succumb to the flames, instead cancelling each other out when the two elements collide.

Weaknesses
The Mera Mera no Mi is inferior to the Magu Magu no Mi in the Devil Fruit hierarchy. Magma is of a naturally higher order than fire, allowing it to overwhelm the Mera Mera no Mi's powers. The magma can neutralize even the intangibility and heat-immunity of the Mera Mera no Mi, thus leading the user to be burned and completely vulnerable. If the magma strikes through the body of the user, it cannot be phased through like most other attacks, and the damage inflicted will remain, as with any normal person's body. Other than that, the user is also affected by the standard Devil Fruit weaknesses.

Portgas D. Ace
The fruit's bestowed powers, as used by Ace, have been used in a variety of ways. Since he left home three years before Luffy, who did not know that Ace had powers before their reunion in Alabasta, Ace had his powers for no more than three years. Ace notably used his powers usually either to fight or to propel his raft. Ace shares Luffy's penchant for naming his techniques, with the only difference being that Luffy adds the phrase "Gomu Gomu No", followed by the specific name of the attack (usually inspired by a certain object or concept). Ace names his attacks in Japanese and they are often made of two-word phrases and are based on different mythologies. According to Gatz, Ace had sunk countless battleships and burned down mighty cities with the fruit's power.

During Ace's cover story, the powers of the fruit allowed Ace to rescue a Marine officer and some documents on board a burning ship. Despite being weakened by the Yami Yami no Mi severely during his fight against Blackbeard, Ace was still able to skillfully use the fruit's power to inflict some damage to his former subordinate.

The named techniques that are used by Ace that involve the Devil Fruit are as follows:
 * Kagero (Kagerō, literally meaning "Heat Haze"): Ace shoots a stream of fire from the palm of his hand. This was first seen being used to stop Smoker from catching Luffy.
 * Hiken (Hiken, literally meaning "Fire Fist"): Ace's apparent signature attack and the source of his nickname "Fire Fist Ace". Ace turns his fist into flames and launches it as a column of fire at his target. This attack is so incredibly powerful that it is able to plow through several ships in one shot. However, it was completely neutralized by Akainu's Dai Funka, and is the final attack Ace ever used prior to his death shortly after.
 * Higan (Higan, literally meaning "Fire Gun"): Pointing the index and middle fingers of both hands at an opponent like guns, Ace turns his fingertips into flames and shoots bullets made of fire from them. This technique was first seen when Ace retaliated against Van Augur's attack.
 * Enkai (Enkai, literally meaning "Flame Commandment"): Ace amasses a large amount of flames around his body (usually by first swinging his outstretched hand around him, summoning the flames) in preparation for an attack. This is apparently the prerequisite technique before Ace can use Hibashira.
 * Hibashira (Hibashira, literally meaning "Fire Pillar"): Used following Enkai,. Ace shoots the collected flames straight upward, destroying a target above him. It can also be fired downwards to clear any enemies that might be below him while he's in mid-air. This technique and its prerequisite technique were first seen when Jesus Burgess threw a hotel at Ace.
 * Hotarubi (Hotarubi, literally meaning "Firefly Light"): Ace creates many small, glowing greenish yellow fireballs that float around an enemy. The idea behind this attack's name is that before he attacks with them, the small fireballs look like fireflies in the air. This move is apparently used in preparation for Hidaruma and was first seen in Ace's battle against Blackbeard.
 * Hidaruma (Hidaruma, literally meaning "Fiery Doll"): After using Hotarubi to send the fireballs floating around in proximity with the enemy, Ace sends them all flying into the target(s) all at once, burning them. This was first seen being used in Ace's battle against Blackbeard after Blackbeard performed his initial attacks.
 * Shinka: Shiranui (Shinka: Shiranui, literally meaning "Sacred Flame/God Fire: Sea Fire"): Ace hurls long lances made out of fire. The lances have the combined effect of simultaneously burning an opponent while piercing them. This was first seen being used against Blackbeard when Ace was being pulled forward by the former's power.
 * Jujika (Jūjika, literally meaning "Cross Fire"): Ace places his index fingers together in a cross shape before launching a cross-shaped column of fire directly at his opponent. In the anime, after crossing his fingers, a cross-shaped ray of light can be seen emanating from the fingers at the target followed by the column of fire. This was first seen being used against Blackbeard after Ace attacked him with Shinka: Shiranui.
 * Dai Enkai: Entei (Dai Enkai: Entei, literally meaning "Great Flame Commandment: Flame Emperor"): Ace's ultimate technique. After creating great spiraling flames centered on his location before amassing it at a focused point (i.e. the palm of his hand), Ace then turns it into a gigantic fireball resembling the sun and hurls it at his opponent to try to obliterate them. This was only seen being used during the final moments of Ace and Blackbeard's battle.
 * Enjomo (Enjōmō, literally meaning "Flame-Up Net"): Ace creates a circle of fire around a selected area, preventing anyone from entering or leaving it.
 * Kyokaen (Kyōkaen, literally meaning "Mirror Fire Flame"): Ace releases a wall of fire to block an attack. This was first seen to counter Aokiji's Ice Block: Pheasant Beak, the two attacks canceling each other out.

Sabo
After Sabo ate the fruit, he has been shown being able to utilize it effectively mere seconds after consuming it. Although struggling to control his new powers at first, he adapted to it, and Sabo has displayed great control over the fruit's abilities, being able to utilize it in conjunction with his pipe and avoid injury by making himself intangible. Like Ace, Sabo names the techniques in Japanese, though Sabo's naming style follows more of his affinity with dragons.

Sabo has been shown using it to enhance the already immense destructive power of his "claws", allowing him to overwhelm powerful foes such as Jesus Burgess.
 * Hiken (Hiken, literally meaning "Fire Fist"): Ace's signature move which was inherited by Sabo after consuming the fruit. Like Ace, Sabo turns his fist into flames and launches it as a powerful column of fire at his target, capable of causing enormous damage and completely shattering a thick layer of stone floor. This was first seen used to destroy the entire Corrida Colosseum stage, and the first move Sabo made since consuming the fruit. He also demonstrated the ability to use the attack at pointblank range, by grabbing onto his opponent's face and then triggering the ignition, sending the target flying backwards with tremendous kinetic force and severely burning them simultaneously, as he did so on Burgess.
 * Moeru Ryusoken: Kaen: Ryuo (Moeru Ryūsōken: Kaen: Ryūō, literally meaning "Burning Dragon Claw Fist: Fire Flame Dragon King"): A combination of the Mera Mera no Mi powers and his Ryusoken style, Sabo forms his "talons" and ignites them, and then slams them into his opponent and spins them around before blasting his target away with a burst of fire. This was first used against Burgess, who was sent flying a great distance away while suffering from burns of the flames.

Trivia

 * The idea of a Devil Fruit that would allow someone to use fire was first brought up when Morgan explained what Devil Fruits are.
 * Its powers were first foreshadowed when Ace visited a town on Drum Island, when it did not snow on that day, although it did for the whole Drum Island Arc.
 * It is the only known Logia Fruit that was not eaten by an antagonist, as Ace and Sabo are both Luffy's brothers.
 * This is the second Devil Fruit to be shown coming back into circulation after its user's death, the other being Smiley's Devil Fruit — the Sara Sara no Mi, Model: Axolotl. However, this is the first Devil Fruit whose possessor was human.
 * The color of Ace's fire changed over the course of the series, originally appearing red-orange to a more yellow orange color. However, when Sabo first used the fruit in the anime, its shade appeared red-orange again.
 * This is the first Devil Fruit known to be eaten by someone after its power had already been given, as Masked Deuce ate part of the fruit shortly after Ace did.