Donquixote Pirates

The Donquixote Pirates is a group led by Donquixote Doflamingo, who goes by the underworld broker alias "Joker".

Past
Not much is known about the Donquixote Pirates before the timeskip, as the term itself did not come up until after. However, Trafalgar Law was once a subordinate whom Doflamingo treated as a younger brother before his defection. Vergo was apparently the first member of the crew, and Law's senior, but before becoming famous, he enlisted in the Marines to serve as a mole on behalf of Joker for the last fifteen years. Eight years before the start of the series, Doflamingo joined the Shichibukai, and the crew was allowed to stay at Dressrosa. The Bellamy Pirates also swore their allegiance to the crew, and was permitted to use its Jolly Roger.

At some point in the past four years, Doflamingo formed a three-way alliance with the rogue Marine scientist Caesar Clown and Kaido, in order to create SAD and SMILE artificial Devil Fruit, to create an army of Zoan-class users within the New World. However, needing Caesar for the SAD production and not trusting him, Doflamingo assigned Vergo and Monet to function as an intermediate and deep cover agent to monitor and protect him on his behalf to ensure his safety of his investment.

Bellamy's Punishment
After Bellamy's humiliating defeat at the hands of the Straw Hat captain, Doflamingo arrived and toyed with Bellamy and dismissed them when their captain was defeated easily, falling out of the expected standards. Doflamingo then goes on about how the world should be prepared the New Era.

Battle of Marineford
While Doflamingo himself participated in the Battle of Marineford, Law, having already formed his own crew and became an infamous rookie, came near the end of the war in order to rescue Monkey D. Luffy. Law succeeds in saving Luffy while Doflamingo emerges from the war unharmed. One year later, Law became a Shichibukai by turning in 100 hearts from pirates and sought shelter in Caesar's hideout, Punk Hazard.

Punk Hazard Incident
During the events of the Punk Hazard Arc, Law revealed his rebellion against the Donquixote Pirates by attacking the SAD production room and attempted to kidnap Caesar by forming an alliance with the Straw Hats. Doflamingo ordered Vergo to brutally eliminate Law, but Law succeeded in defeating his senior and, indirectly, killing Monet. Doflamingo, in turn, sent Baby 5 and Buffalo to clean things up and retrieve Caesar, and, upon seeing that Monet failed to detonate the island's chemical weapon as ordered, decided to enter the island himself. However, Baby 5 and Buffalo are swiftly incapacitated by the Straw Hat Pirates, and then Caesar was also captured after his failed attempt to escape alone to Dressrosa.

Taking Caesar hostage, Law cut apart Buffalo and Baby 5, and left their heads on the SAD tanker's rescue raft to drift towards the incoming Doflamingo, with a Den Den Mushi to contact him. Law threatened his former captain to resign his Shichibukai position to continue negotiations with Caesar as the collateral.

After his attempt to kill the G-5 Marines being thwarted by Kuzan's arrival, Doflamingo retrieved Baby 5 and Buffalo, body and head, and returned to Dressrosa. Fearing Kaido's wrath, Doflamingo immediately resigned from the Shichibukai, forfeiting his kingship in Dressrosa as well, leading to a massive uproar in the kingdom and the world beyond it.

Crew Strength
The Donquixote Pirates is a very powerful crew, as their captain is a world famous pirate, a former member of the Shichibukai with a bounty of 340,000,000 and the former ruler of the kingdom Dressrosa. Crew members Monet, Baby 5, and Buffalo are all known Devil Fruit users, while Vergo is a mole who has ascended the Marines ranks for about fifteen years, eventually becoming a vice admiral, while keeping his true identity hidden from everyone outside of his affiliates. Vergo alone has shown to easily defeat Law, a Shichibukai level opponent twice with little effort (though Vergo did have Law's heart twice to help him) and defeated Smoker, a Logia fighter with moderate difficulty(though smoker's intention was to  retrieve law's heart).

They are heavily involved in underworld brokering (including slavery, and production and distribution of weapons of mass destruction) in the New World, making them both very influential and very powerful. They are known to have destroyed entire towns at whim, as stated by Baby 5. The crew also seems to excel in teamwork, as when Baby 5 and Buffalo fought Franky Shogun, there teamwork was near flawless and demonstrated great skills in using each others powers for combat. The crew also once consisted of Trafalgar Law, a powerful pirate rookie who would go on to become a Shichibukai as well, with a former bounty of 440,000,000, prior to him leaving for his own interests. Law was considered by Doflamingo for a place among his four top subordinates, meaning that these crew members are likely on par with the Heart Pirates captain in terms of strength.

The crew are also allied with Vegapunk's former colleague Caesar Clown and have him produce SMILES to be sold in the underworld. The scientist is the only person able to produce a substance called SAD, something which Doflamingo places value in greatly. They are also in an alliance with Kaido, one of the Yonko, having supplied him with SMILES for his Zoan army. Having powerful allies such as these prove the Donquixote Pirates are a forced to be reckoned with.

Ship
The SAD Tanker (SADのタンカー) is a tanker used for carrying SAD from Punk Hazard to Dressrosa. It first appeared in Chapter 692, when Caesar smashed into it.

It is a paddle-wheel driven ship with three masts. At its bow is a spherical figurehead bearing the jolly roger of the Donquixote Pirates and a safety rail. Further aft of the bow are two large domed tanks with openings at the top, radioactive symbols on the sides, and hazard stripes around their circumferences. The masts are positioned immediately in front, behind, and between the tanks. They have dark sails and at least one of them has a crow's nest with a flag at the top. On the ship's hull is the Donquixote Pirates' jolly roger, the letters SAD, and an awning that partially covers the paddle-wheels. The ship is partly caked with Shinokuni since it was outside at the time of the gas's release. The hull also has two holes in it due to Caesar Clown crashing through it. The bridge is a flat, multi-story building with two buttress-like beams jutting out from the top. Despite its appearance, the bridge is actually quite spacious, as Law turned it into a sick bay so he could cleanse the imprisoned children of the drugs Caesar put in them. On either side of the roof are two small spires.

Usage
When Vergo heard that an SAD tanker was heading to Punk Hazard from Dressrosa, he caught a ride on instinct. Upon learning about it, Smoker ordered his contingent to lead the children to safety and then commandeer the idling tanker.

Later, the tanker was covered by Shinokuni, but most of it was removed when Luffy's punch sent Caesar Clown crashing into it, which also put two holes in the hull. Franky was examining the ship in Franky Shogun, when he emerged and saw Buffalo and Baby 5 in the sky. He later engaged them from the deck of the tanker. Two of the masts were destroyed during this battle.

Once the battle was over, the G-5 Marines seized the tanker in order to transport the children as well as the underlings they had apprehended on the island. Franky was helping them repair the damaged mast, saying they should have told him sooner that the tanker was important. He said he would have moved the fight off the tanker's deck if he had known that it would be needed. Law gave the children treatment to detoxify their bodies in the bridge, which frightened Chopper. After seeing that they were all okay, he told them they would be going home. It was also in the bridge that the children were put in the custody of Tashigi and the Marines, the latter of whom tearfully asked Nami to leave the children under her watch. Soon after, Zoro and a child asked a Marine to get some alcohol and juice from the tanker so they could have it with the food Sanji was making. Later, the Straw Hats gave tanker to the Marines so they could use it to take the children home.

Other Information
The Donquixote Pirates are a very powerful crew in both strength and influence. Being connected with the underworld, they have formed many alliances, ranging from brokering to spies within the Marines. They also managed to recruit significant individuals and entire pirate crews to become their allies, such as Caesar Clown and the Bellamy Pirates. Prior to the latter's dismissal, Bellamy and his crew were attempting to recruit promising pirates for the "New Age" under the Donquixote Pirates' insignia. The crew also formed an alliance with Kaido of the Yonko to create an army of artificial Zoan-class Devil Fruit users, which involves the SAD that only Caesar could produce. However, this alliance is based more on terror, as even Doflamingo fears Kaido's immense power, and goes into hysteria when the contract was threatened. Their base of operations is Dressrosa, a New World kingdom with a luxurious castle, a swimming pool and a factory where SAD is processed into Smiles, where Doflamingo was the king due to his position as a Shichibukai. Several members and allies, such as Law and the Bellamy Pirates, originate from North Blue, although whether the crew originates from there is unknown.

In terms of interpersonal relationships, Doflamingo values the members of his crew somewhat like a family, albeit with tendencies of harsh punishments for failures; he saw Law and Baby 5 as though they were younger siblings, but demanded the former's death in the most brutal fashion possible for betrayal. He also abandoned Monet and Vergo when they were defeated, ordering them to commit a suicide bombing to annihilate all evidence and enemies within, though he expressed sincere regret for forcing them to do so; in turn, both Monet and Vergo, at least, were glad to give up their lives for Doflamingo, and happily bid him farewell. Doflamingo also treasures his alliance with Caesar, if only for the scientist's ability to produce SAD, but has no patience for other allies who fail to meet his standards, as he tortured and discarded the Bellamy Pirates and later disowned the Human Auctioning House for respective reasons. The members refer Doflamingo as "Young Master" (若) as a sign of respect, or by his alias "Joker" for discretion.

Similar to the Straw Hat Pirates and Big Mom Pirates, the Donquixote Pirates seem to have a wide and randomized variety of crew members, as opposed to many crews that follow a specific theme, ranging from a young girl to elderly people. Though it seems that several members have some personality quirks that Doflamingo is willing to look past, such as Vergo's absentmindedness, Baby 5's inability to refuse any request, Trébol's tendency of getting physically close when communicating, and Diamante's constant denial of flattery until it has been retracted.

It appears there is a system of ranking reserved for the more important or powerful members, to which they are allowed to sit on seats represented by the four suits of cards: Heart, Club, Diamond and Spade. The Heart was reserved for Law, though his defection made it vacant, while the Club and Diamond belongs to Trébol and Diamante, respectively; the Spade is yet to be revealed. The four who are situated at these seats are apparently quite respected, as Baby 5 used an honorific to refer to Trébol.