What happened at Ohara?

Ohara was an island of scholars dedicated to studying history — specifically the Void Century, the 100-year gap in recorded history that the World Government had erased. When the scholars' research threatened to uncover what the government wanted hidden, a Buster Call was ordered: a fleet of Marine warships destroyed the island. Everyone on it was killed.

How old was Robin?

Eight years old. She had the Devil Fruit ability (Hana Hana no Mi) from childhood, was already assisting the scholars, and was betrayed — her location reported to the Marines before the attack. She escaped alone on a small boat.

What was her mother's role?

Nico Olvia, Robin's mother, had left Ohara years earlier to research Poneglyphs secretly. She was captured by the World Government. She returned to Ohara during the Buster Call — and watched the scholars die, and saw Robin on the burning shore. She chose not to reveal their relationship, to protect Robin from being specifically targeted. She died with the island.

What happened to Robin after Ohara?

Twenty years of running. The World Government placed a bounty on an eight-year-old and told the world she could destroy countries with her abilities. Every person who took her in eventually turned her over for the reward. She learned not to trust. She survived by being useful — making deals, offering intelligence, serving anyone who could protect her temporarily. She had no home.

What does Ohara represent thematically?

The organized destruction of knowledge by power. The Void Century is the thing that cannot be known — the World Government's foundational crime. Robin's entire life is the consequence of powerful people's determination to keep that secret. She's the last scholar of Ohara because they couldn't kill the eight-year-old they'd made into a fugitive.