WARNING: The following article contains SPOILERS for Arrow up through "The Dragon"
Despite the wishes of many fans, the sixth season of Arrow has failed to redeem Black Siren. The series hasn't been able to develop the evil doppelganger of Laurel Lance into a proper character, in addition to struggling to produce a storyline that would allow her to make amends for her many misdeeds.
Black Siren was originally introduced into The Arrowverse in "Invincible" - the penultimate episode of the second season of The Flash. She was a highly-placed lieutenant in the metahuman army of Zoom - the super-speedster crimelord who ruled over the parallel world of Earth-2. After Zoom was defeated, Black Siren was imprisoned in The Pipeline - the secret metahuman prison under STAR Labs.
Black Siren was liberated from The Pipeline later that year by Prometheus - the main villain of Arrow's fifth season. She was all too eager to join Prometheus in his bid for revenge against Oliver Queen, who had killed Prometheus' father during his early days as a vigilante. She briefly posed as the Earth-1 version of Laurel Lance, claiming to have been restored to life by the Legends of Tomorrow. The terminally impatient Black Siren quickly blew her cover and tried to kill Oliver Queen and Felicity Smoak.
Despite this, she still tried to play upon Oliver's sympathies, spinning a sob story about how she had dated the Earth-2 version of Oliver Queen before his death sent her down the road that turned her into a metahuman criminal. Ultimately, she still stood with Prometheus and his allies during the climactic finale of Arrow's fifth season, in which the prison island of Lian Yu was destroyed. Black Siren survived the devastation, however, and led a group of armed mercenaries in an assault on Star City's Police Headquarters in the Season 6 premiere, "Fallout".
When Season 6 of Arrow started, Katie Cassidy claimed in one interview that the new season would explore Black Siren's backstory and "what her relationship was like with [her version of] Oliver." Unfortunately, this did not come to pass. The only new details regarding Black Siren's past on Earth-2 involved her father dying on her thirteenth birthday and the revelation that she had never gone to college, earned a degree or even held a real job in her entire life.
To say that the efforts to build up Black Siren have been disappointing would be an understatement. We've learned nothing about her relationship with her mother, whose Earth-1 incarnation is a history professor in Central City. Nothing has been said about whether or not there is an Earth-2 version of Sara Lance - Laurel Lance's younger sister, who became The Canary and then White Canary on Earth-1. We haven't even learned if she was living the life of a criminal before she gained her metahuman powers or if her apparent skills as a thief and assassin were developed later.
Related: Why The CW Needs To Cancel Arrow
A larger and more disturbing problem has been the efforts of Quentin Lance to try and force redemption upon Black Siren over the course of Season 6, claiming that there has to be some good in her because his daughter was good. This insistence came shortly after it was revealed that Black Siren went through her teen years without a father. It diminishes Black Siren's agency as a character to suggest that all of her issues ultimately come down to her just needing a daddy.
Ignoring that, the plain truth is that Black Siren has not shown any honest signs of wanting to redeem herself or being worthy of a second chance. The past two years have seen her gleefully commit numerous acts of terrorism, theft, destruction and murder. She claimed to have been forced into helping Zoom and Prometheus, yet she went back to helping Prometheus despite being offered a shot at freedom. The sixth season has seen her ally herself with Cayden James and Ricardo Diaz - two ordinary humans who could hardly force Black Siren to obey them. She's even become romantically involved with Diaz.
The failure of Arrow to sell Black Siren's redemption arc peaked in "The Dragon." The episode concluded with Black Siren looking disturbed as Ricardo Diaz killed the bully who tormented him as a child by burning him alive. This reluctance might have been more convincing had Black Siren not spent most of the episode (and indeed the season) complaining about not being allowed to kill wantonly. It didn't help matters that she was party to a far more grisly murder - turning a man into a suicide bomber after slowly torturing him - earlier in the episode. Hopefully the Arrow season finale, which will include the return of Sara Lance, will see White Canary giving Black Siren the beating she so richly deserves and reminding Quentin what a daughter's love is really like.
Arrow returns on Thursday, April 27, with "Shifting Allegiances".