Caesar Clown

Caesar Clown (シーザー・クラウン Shīzā Kuraun), also referred to as "Master" (マスター, Masutā) by his underlings, is a former colleague of Vagapunk and the main antagonist of the Punk Hazard Arc in the anime and manga, One Piece. Caesar is the leading expert on mass-murder weapons and is a mad scientist with a bounty of 300,000,000 beri on his head.

Personality
Caesar Clown is perhaps one of the most sadistic characters in One Piece as he enjoys seeing people suffer. He pretty much cares for himself than anyone else and has shown to be very deceitful and manipulative such as when he rescued a crew of pirates and helped them but instead used them for his cruel experiments. Caesar also has no remorse for his actions and will sacrifice children for his experiments with any care for them. When it came to Brownbeard and his crew, Caesar sees them as "guinea pigs" who are scum of the earth that people would not care for if they died, this shows how much he saw them as tools and just how vile he truly is. He does not care for the safety of anyone as he will even allow Shinokuni to kill off one of his comrades, Vergo, if it means that the Marines and the Straw Hats die from it as well. Caesar is very prideful as being one of the best minds in science and sees himself as a better scientist than Vegapunk, his rival, and has shown to be incredibly jealous of the latter. Despite his overall selfish and psychopathic personality, Caesar praises Donquixote Doflamingo and respects him because of the protection the latter gives him to do his experiments.

At times, Caesar can be dramatic and silly as he overacted over having his heart crush even though it is not his real heart. Like Spandam, Caesar will run away from a problem that he started and will try to talk himself out of a situation. And like the latter, he has a temper.

Abilities
Caesar has the Gasu Gasu no Mi which is a logia type devil fruit that grants him the ability to turn into gas. With this ability he can become intaginable but he can still be by anyone using Haki. Caesar's use of manipulatin gas can also be used to even suck the oxygen out of the air to suffocate his opponents. Caesar can shoot laser beams from his mouth by using manipulating the gas which can cause an explosion. He can also make the gas around him become poisonous and flamable to be used in battle. Before he got cuffed by seastones by Ussop, Caesar has shown to have his devil fruit active at all times. When Caesar merged with Shinokuni, he was able to petrify targets near him and have control over the gas at a longer distance.

Besides his devil fruit abilities, Caesar also carries around a gun and he is also good at using a sword in battle. Caesaar is also castenets which he calls "Gastenets" which he uses to create giant explosions by manipulating the gas in the air. He is also a very intelligent scientist as he was the capable of making artificial devil fruits, weapons (mostly weapons of mass destructions), and conducting other experiments. Caesar also posses superhuman strength as he was able to swing his sword at an immense speed while fighting Luffy and withstanding powerful blows to the face by the latter.

Past
Caesar used to work for the Marines on Punk Hazard with his rival Vegapunk. One day, Caesar was annoyed at Vegapunk appearance. Caesar decided to blow up the island killing many people, destroying the vegetation and wildlife on the island, and becoming a criminal of the World Government. Caesar remamined on the island for sometime where he helped out people who drifted ashore on the island but in reality he was manipulating him. At some point, Caesar began to work for Doflamingo where he created artificial devil fruits to empower Kaido's army.

During the timeskip, he was confromted by Law who wanted to join his team. Caesar decided that Law should give Monet his heart for her own heart to prove his loyalty to their group.

Punk Hazard Arc
Caesar was first appeared when the remaining Straw Hats broke out of their cell and was interested in Franky because of how his weapon system that came from Vegapunk. He was surprised to know that the G-5 Marines were on the island and was shock to hear that the Marines saw the kidnapped children. He was also surprised learn that the Straw Hat Pirates' were present on the island. Caesar then blames Law for allowing the Marines to see the children. He later contacts Joker who gave him permission to kill off all the intruders on the island. He later killed off a centaur troop member after he told him that Brownbeard got captured by the Straw Hats to test out his experiments that he deemed was anything but a failure. He told Monet that he was the best scientist out there and all his experiments were not a failure. Law later returned to give Caesar, Smoker's heart and revealed to Law that he sent the Yeti Cool Brothers to capture Franky and kill the Straw Hats including Brownbeard. At first, Caesar was skeptical about Law's loyalty to his group because of his relationship with Monkey D. Luffy in the past. He decides it was safe with Law and revealed to him that he was druging the children to keep them on the island much to Law's disgust. Caesar later relaeased his pet Smiley to unleash chaos on the island and went outside to see it in progress. Once outside, he was ambused by Luffy (who was going to capture) him and got into a fight with him where he defeated him, the Straw Hats that was with him, and the Marines.

Caesar later went to the hiding spot where Nami and Ussop and defeated them, to the children, and mocked a beatened Brownbeard. Back at the laboratory, Caesar confronted Law on his betrayal and the captured Straw Hats and Marines and proceed to torture Law by crushing his heart (that Vergo gave him) because the latter insulted him. He then turned his attention to Shinokuni (the rising poisonous gas) and then broadcast it to people on the black market who wanted it. He later released the captured Straw Hats, Law, Smoker, and Tashigi outside to allow them to die by Shinokuni. He attempted to kill off many people on the island by trying to expose them to Shinokuni. After some time pass, Caesar was confronted by Luffy again, where he got into another fight with him but escaped and left Monet to deal with the pirate. Caesar was later contacted by Doflamingo and was ordered to return to Dressrosa with Monet and Vergo because of what is happening on the island. He was later seen with subordinates and ordered them to allow Shinokuni to flow through the building to kill off the enemy. Brownbeard later appeared and tries to warn his comrades about Caesar. But Caesar manipulated the situation to make Brownbeard look like a traitor to his comrades and continued to mock him by whispering to him. When Caesar was about to land a finishing blow on Brownbeard he caught off gaurd by a Haki-infused punch to the face by an angry Luffy.

Caesar tries to explain to Luffy that if anything happens to him then he will have to face bigger threats in the New World like Doflamingo and Kaido. Luffy ignored his words and punched Caesar in the face again. After Law leveled the island with his attack, Caesar viciously ordered his subordinates to release Shinokuni into the room to power him up at the cost of his teammates safety. When Caesar fused with Shinokuni he tried to kill off everyone in the room but was easily defeated by Luffy with a Haki infused attack and was sent reeling outside the building. After regaining consciousness from the attack and seeing Baby 5 and Buffalo fight Franky, Caesar attempted to kill Smoker by stabbing him in the heart but unknowingly killed Monet. Later after seeing the Straw Hats, Marines, and children outside of the building unharmed, he tried to go Dressrosa on his own but was captured by Ussop and Nami and was cuffed with seastone. Caesar was later seen being interrogated by the Marines on how to undo the effects of Shinokuni. After the Straw Hat crew treated the children for their poisoning, Law incapacitates Baby 5 and Buffalo, and wrapping up few other problems, Caesar was captured by the Straw Hats and Law in their attempt to dethrone Doflamingo position as a Shichibukai.

Dressrosa Arc
On the Sunny Ship, Law allowed Caesar to talk to Doflamingo to prove his safety. Once everyone arrived to Dressrosa, Caesar was put into a group with Law, Robin, and Ussop where they decided to head to Green Bit to meet Doflamingo. When they were in town, they had to put on a disguise and then wait for the time to meet Doflamingo at the bridge. When they were battling the Fighting Fish on the bridge to Green Bit, it was revealed that Law took Caesar's heart much to the latter's shock. After Robin and Ussop separated from the group, Doflamingo and Admiral Fujitora appeared. Doflamingo revealed to them that he was still a Shichibukai much to Caesar's delight. As the fight between the Admiral and Shichibukai commenced, Caesar and the Marines ran into the forest to avoid the dangerous clash. After the fight was over and Law lost, Caesar wanted to know where his heart was. Law then escaped from a distracted Fujitora and grabbed Caesar to return him to the Sunny ship where the Straw Hats (Sanji, Brooks, Nami, Chopper, and Momonosuke) were because Doflamingo did not honor his deal. Law decided to give Caesar his heart back and revealed that he had it inside himself for most of the time.

Now deciding to sail away from Dressrosa to escape from Doflamingo, the Straw Hats were planning to sail to the next island, Zo, but Big Mom's ship appeared and her subordinates wanted to capture Caesar. Caesar was frightened because he used to embezzle from Big Mom and did not want to suffer her wrath. He begged the Straw Hat pirates to save him which they reluctantly agreed to do only because it is apart of their overall plan to take down Kaido.

Trivia

 * Caesar was the title for the Roman emperors, derived from the cognomen of Julius Caesar.
 * Like Magellan, Caesar's sinister face, wild hair and horns make him resemble a stereotypical image of a demon; particularly Baphomet, a pagan deity-turned-devil most commonly depicted as a humanoid goat.
 * In his first appearances his coat did not show "GAS" written twice on the front as it does in Chapter 666 and Chapter 671.
 * He is also, so far, the only Devil Fruit user who seems to keep his Logia Devil Fruit active all the time, giving him his gaseous appearance.
 * He is the second Devil Fruit user to alter the properties of his own fruit's power using artificial chemicals, the first being Tony Tony Chopper with the Rumble Balls.
 * Caesar's Japanese Voice Actor, Ryūsei Nakao is largely known from his previous roles in other Anime such as Mayuri Kurotsuchi from Bleach and in One Piece: Strong World as Indigo. Oddly enough, all three individuals have similar behavior and position (crazy, sadistic scientists).
 * In Chapter 663, his name is spelled as "Caesar Clown" which takes place of the hiragana, as seen Smoker's monologue. However, in Volume 68's character introduction, it is spelled as "Caesar Crown".