Donquixote Doflamingo is a member of the shichibukai and the current king of Dressrosa. He is also a descendant of the Donquixote family, a family formerly affiliated with the world nobles.
Doflamingo was born into a family of nobility, the Donquixote family. He apparently really cared for his mother, who died of an illness right before Doflamingo's eyes. This seems to have stuck with him, and likely helped shape him into the madman he is today. According to Doflamingo, he blames the death of his mother on his father, whom he strongly resented.
Because Doflamingo was born a world noble, he was used to living a spoiled life of luxury and generally being treated above others. Doflamingo's father, Homing, did not share Doflamingo's view on being a noble and resigned from nobility to try to live a normal life with his family.
Due to their nobility, the Donquixotes were targeted by angry commoners of their country due to their hatred against world nobles. This forced them to leave their home and settle in a makeshift shack. Eventually, the angry commoners found the Donquixotes and Doflamingo, his brother Rosinante, and father Homing, were lynched and severely beaten. This event left Doflamingo completely traumatized, and he has suffered from PTSD ever since.
At age 10, Doflamingo decided to shoot and kill his father in an attempt to regain his nobility. He brought his father's head all the way to the Celestial Dragon's homeland, Mariejois, where he presented it to the Celestial Dragons, who rejected it, siting a family of traitors as their reasoning. However, Doflamingo discovered a secret of the Celestial Dragons and used that to blackmail them into returning his lost rights.
At some point after, Doflamingo met Vergo, and Trebol, and decided to form his own pirate crew.
At age 17, Doflamingo was present at the execution of the Pirate King, Gol D. Roger.
At age 24, he was reunited with his brother, Rosinante, who replaced Vergo as Corazon on Doflamingo's crew. Despite being brothers, Rosinante was secretly undercover as a marine, plotting to take down Doflamingo and his crew. Rosinante was under the guise of pretending to be deaf and stupid, using his Devil Fruit ability (Nagi Nagi no mi, which grants its user to be completely silent) to assist his charade.
At age 25, Doflamingo was approached by a ten year old boy named Trafalgar D. Water Law, who was suffering from Amber Lead sickness.
Around three years later, Doflamingo discovered his brother's treason and shot and killed him in cold blood.
At some point, he and his crew sabotaged the country of Dressrossa by appearing to have the former King Riku and his army slaughter the people of the country in an attempt to demonize the Riku family. Doflamingo and his crew then came in and "stopped" them, causing the people of Dressrosa to view them as heroes. With that, Doflamingo became the next king of Dressrosa and reclaimed families country.
At some point later, Doflamingo became a prominent underground broker under the alias "Joker." He formed a partnership with Caesar Clown to produce artificial Zoan-Class Devil Fruits known as SMILE, which he dealt to one of the Yonko, Kaidou.
Doflamingo seemingly has a lot of aliases that he is called by. Many of his subordinates and the people of Dressrosa address him as "Young Master," Fujitora refers to him as "Heavenly Demon," his underground alias is "Joker," and some of his most trusted crewmates refer to him as "Doffy." Monkey D Luffy refers to him as "Mingo."
Doflamingo had a bounty of 340,000,000 Belly, though due to his status as shichibukai, that bounty is waived.
Doflamingo is generally very lax and often comes off as being very arrogant. When shown he is almost always seen smiling.
As a child, Doflamingo shared many traits of typical noble. He was spoiled, wanted to own slaves, and generally viewed himself way above the commoners of the world.
He seems to always want to be in control of everything, as evidenced when Monkey D Luffy had entered the palace, he was under the impression he was still fighting under in the Colosseum under the name "Lucy." This caused the normally lax and arrogant Doflamingo to become enraged.
Despite his arrogance, Doflamingo seems to know his limits. He chose not to engage former Marine Admiral Aokiji, and he is apparently terrified of the Yonko, Kaido.
Doflamingo is also fearful of those who bear the initial "D" and views them as demons.
Power and abilities
Doflamingo is a shichibukai, and as such, possesses great combat abilities and strength. He is capable of using Conquerors Haki, which only one in a million people can do.
Doflamingo is the current user of the Ito Ito no mi (String String Fruit) which allows him to expel razor sharp strings from his body. This ability has been used in various unique ways, such as being used to slash people/objects, take over people's bodies like a puppeteer, and even summon and a razor sharp cage around Dressrosa so nobody could escape. As long as there are clouds in the sky, Doflamingo can also use them to fly through the sky as a means of transportation.
A testament of Doflamingo's strength can be seen when he effortlessly defeats Smoker, a vice admiral, and even temporarily engaging with Fujitora, an admiral.