The only survivor of the Ohara Incident, said to be one of the few individuals capable of reading the Poneglyphs, Nico Robin endured a tumultuous journey before joining the Straw Hats. Wanted by the World Government for the knowledge she possessed regarding the research done by the scholars of Ohara, Robin spent much of her childhood and youth on the run, repeatedly betrayed by those she sought refuge with, to a point where she was unable to trust anyone. Towards the start of the One Piece, she finally found some measure of stability with Baroque Works, where she was second in command to the Warlord Sir Crocodile, taking on the alias of Miss All Sunday.
One of the underlying themes of Robin's journey has been reclaiming the sense of family she lost with the destruction of Ohara and the passing of her mother Nico Olivia in the same event. Having a sizable bounty on her head from childhood did her no favors, and she was also forced to fend for herself at an early age in a harsh and unforgiving world, and made with the power of the Hana Hana no Mi, which greatly bolstered her prowess in combat. After the defeat of Crocodile and disintegration of Baroque Works at the end of the Arabasta Saga, Robin joined the Straw Hats as their sixth member, finally discovering what it meant to have a family again. However, this happiness was short-lived as her past came back to haunt her in Water 7, in one of the most gripping arcs of the series. Despite nearly leaving the crew after being captured by CP9, Robin was welcomed back with open arms and has been an integral part of the group's quest to decipher the Poneglyphs and find the mythical treasure that is the central focus of One Piece.
The Tragedy Of Ohara
Having been recognized as a scholar at only eight years of age, Robin spent most of her early years in the Library of Ohara, encouraged by its director, Professor Clover, to pursue her interest in archeology. Left to live with the family of her mother's brother, whose wife, Roji, routinely subjected Robin to both verbal and physical abuse. In addition, she was also ostracized by the other children living on the island due to her unique Devil Fruit abilities. On declaring her intention to study the Poneglyphs and learn the true history of the Void Century, Robin was admonished for her actions by Clover, who sought to safeguard the child from the path chosen by her mother, Nico Olvia. This led her to find solace with the Vice Admiral Jaguar D. Saul, a friend of her mother's, who had washed ashore on the island.
Saul, who hailed from Elbaf, warned Robin of the impending wrath of Marine battleships summoned to carry out a Buster Call and destroy the island, and told her to flee from Ohara as soon as possible. In the process, Robin had a close brush with her mother, but neither of them were able to take notice of the other, delaying their reunion until it was too late. The death of Professor Clover at the hands of the Marines, followed by the capture of Olvia and the invasion of the island commenced the horrific sequence of events that would later to be known as the Tragedy of Ohara. Although Robin finally met her mother, her happiness was short-lived, as Olvia urged Saul to take Robin away with him and escape the advance of Marine battleships, which had now taken over the island. Saul took Robin to the boat he had been building, only to encounter Kuzan — the future Admiral Aokiji — who froze Saul but allowed Robin to escape. With tears streaming from her eyes, Robin fled the island of Ohara, saying goodbye to the only home she had known. Losing the only family she had was a devastating experience for Robin, one that would shape her life for years to come.
The Demon Of Ohara
When the World Government found out that Robin was capable of deciphering the Poneglyphs, they immediately issued a bounty of 79,000,000 berries. Labeled the "Demon of Ohara," who was falsely blamed for sinking six battleships, Robin struggled to find any semblance of safety while taking refuge with anyone. Betrayed by virtually everyone she came to trust over the 20 years she spent as a fugitive from the World Government, Robin grew to despise the World Government for how they ruined her life. She yearned to find a home again, and be surrounded by those she could trust. As time passed, she became wary of those who were ready to discard her in order to further their own objectives, double-crossing them before they could use her for their personal gain.
Robin made her way to Grand Line from the West Blue, where she met with Sir Crocodile, who, at the time, was one of the Seven Warlords of the Sea. Since he needed her skills in reading the Poneglyphs to achieve his own goals, Crocodile recruited her into Baroque Works, an organization he founded in order to destabilize and take control of the Arabasta Kingdom. Here, she found a safe haven from the Marines, spending a total of four years in Crocodile's employ, rising to become one of the highest-ranking officers in the organization.
Finding Home With The Straw Hats
Despite being an antagonist when first introduced, Robin went on to join the Straw Hats after Luffy defeated Crocodile, and accompanied them on their journey to Jaya and Skypiea. The crew subsequently reached the city of Water 7, where her past came back to haunt her once again. Apprehended by CP9 agents acting on the orders of Spandam — son of Spandine, who was responsible for the Ohara Buster Call — Robin was taken to Enies Lobby, to be interrogated about the location of the Ancient Weapon Pluton. On learning of this Luffy and the Straw Hats journeyed to the government stronghold and declared war on the World Government to save Robin. An intense battle ensued where the CP9 agents led by Rob Lucci, were defeated by Luffy and his crew, who saved Robin and showed her that she would always have a home with the Straw Hats.
It was this act that made Robin finally realize that she had found the family she had desired for so many years. She dedicated her life to help Luffy achieve his goal of becoming Pirate King, and in the process, sought to fulfill her own dream of uncovering the true history of the world. Through every successive arc, Robin has grown into her role as the crew's archeologist, finally dealing with her trauma from the fall of Ohara. As time healed her wounds, she has also let go of her more stoic demeanor from prior to the time skip, instead taking on a more playful and caring persona while still remaining steadfastly loyal to Luffy and her fellow crewmates above all else.