SPOILER WARNING: This article contains major spoilers for "Inheritance," the latest episode of Arrow.
Arrow just rewrote its own history. In "Inheritance," the latest episode, a flashback revealed Emiko was the one who sabotaged the Queen's Gambit, killing her father Robert and sending Oliver down the path that would lead him to become Green Arrow.
The episode revealed Emiko's history through a series of flashbacks, beginning the day Robert abandoned them. Without his money, Emiko and her mother were left destitute. She turned to the streets for work at the tender age of 11, even running errands for the Bertinelli crime family. She met Dante as their courier, only to switch her allegiance when he promised to show her how to defend herself.
Emiko worked with Dante for years, honing her skills as a fighter and archer. When she was old enough, he offered her a gift and told her she must choose between her family and the Ninth Circle; after all, the Ninth Circle was a lifetime commitment. She hesitated and decided to give Robert another chance. However, when she approached him with a business plan for Queen Industries, he turned her down because the company would go to Oliver -- and because he feared that people would learn she was his daughter.
Devastated, Emiko opened Dante's gift. In it, she discovered the plans to the Queen's Gambit, the boat which Robert had told her he would be taking a trip on. The episode closed with a shot of Emiko burning the plans as a news story announcing her father's death played in the background, suggesting she was the one who sabotaged the ship.
Following this, Emiko dedicated her life to the Ninth Circle. As revealed in "Inheritance," she ranks even higher than Dante. When he disobeyed her order to perform a demonstration, she informed him she would kill him if he ever disobeyed again. It is unclear how high the chain of command goes in the Ninth Circle, but she appears to be part of the inner circle.
In Arrow's original canon, Malcolm Merlyn was the one who sabotaged the Queen's Gambit and caused it to sink. In the Season 1 episode "The Undertaking," a flashback revealed Malcolm planted a bomb on the boat when Robert decided to stop their plan to destroy the Glades. However, per "Inheritance," it seems there's more to this story than meets the eye; worse, the implication is that Emiko killed her own father and set in motion the events that led to Oliver's transformation into the Green Arrow.
Airing Mondays at 8 pm ET/PT on The CW, Arrow stars Stephen Amell as Oliver Queen, David Ramsey as John Diggle, Emily Bett Rickards as Felicity Smoak, Rick Gonzalez as Wild Dog, Juliana Harkavy as Black Canary, Colton Haynes as Arsenal, Kirk Acevedo as Diaz and Katie Cassidy as Black Siren.