Warning: The following contains SPOILERS for The Flash, season 6, episode 12, "A Girl Named Sue."
Sue Dearbon is the most interesting character to be introduced into The Flash in several years. This is all thanks to how well the show has adapted the character from the comics, while introducing a novel twist that turned her into far more than the typical superhero love interest.
Sue Dearbon was introduced into the The Flash comics in 1961 as Elongated Man's wife. The two were newlyweds in her first appearance in The Flash #119, where it was revealed that Ralph Dibny had made enough money doing personal appearances to retire and had apparently won the heart of the young debutante in the process. A retcon later put a bit more romance into their meeting, with Elongated Man and The Flash ing forces to save the same high society affair from a gang of robbers. While most of the crowd were dazzled by the Scarlet Speedster, Sue Dearbon only had eyes for the Ductile Detective and the two fell for each other instantly.
While the gangly gumshoe seemed an unlikely match for an idle heiress on paper, Sue was far more than a trophy wife. Indeed, Sue proved to be a woman of many skills, which she put to work helping Ralph in his work as a detective. Sue was also unique in that she earned an invitation to the Justice League, acting as the bureau chief for the team's embassy in Paris during the Justice League International era.
"A Girl Named Sue" brings Sue Dearbon into the Arrowverse, after teasing Ralph Dibny's search for her throughout season 6. Hired by Sue's parents to investigate her mysterious disappearance, Ralph finally caught up with Sue just in time for her to save him from a bomb. Sue claimed that she had gone on the run after discovering her ex-boyfriend was a criminal and Ralph agreed to help her gather the last of the evidence she needed to send him to prison, so that she could return home.
Sadly, Sue had played Ralph for a patsy, using him to break into a bank vault that contained a priceless diamond rather than incriminating papers. The truth was that Sue had abandoned a life among the landed gentry to become a thief, and the story about a criminal ex trying to kill her had been meant to play on Ralph's sense of chivalry. Despite this, Ralph still saved Sue's life when they were ambushed by the crime boss Sue had robbed, but she still got away with the diamond. The whole affair left Ralph more determined than ever to track down Sue.
The conclusion of "A Girl Named Sue" is reminiscent of the a Black Hole emblem hidden inside of it, suggests there is far more to her motivations than simple thievery and alleviating boredom.