- "I didn't spend 5 years risking my life and my freedom to just be okay."
- —Kyle Reston on the gang's motives[src]
The Royal Flush Gang was actually a family of criminals whom Robert Queen had taken advantage of when he laid off their patriarch Derek Reston, one of 1,500 former employees who never received a severance package thanks to a loophole in his Union contract. This resulted in the Reston family losing their home shortly before the Queen's Gambit sank. 
To finance themselves and to ensure their family's financial security, they resorted to a three-year crime spree, originally operating with the intention of just stealing enough money so that they could live comfortably for the rest of their lives. They did, however, try to avoid hurting people whenever necessary. Whether this was out of a moral code of not wanting to harm innocents or simple common sense for not wanting additional heat from law enforcement is unknown. 
Second gang with an uncertain connection to the first one had surfaced in Keystone City in 2015, evading capture by police using keen strategy and motorcycles. They managed to evade The Flash by splitting up, as well, but using a strategy proposed by Harrison Wells he quickly cornered them by creating detours and stripped them of the keys for their transport, leaving them for police to arrest. 
- Derek Reston/King (leader, status unknown)
- Teddy Reston/Jack (incarcerated)
- Mrs. Reston (incarcerated)
- Kyle Reston/Ace (incarcerated)
Behind the scenes
- In DC comics, the Royal Flush Gang is a legacy name of a gang who opposed the Justice League on several occasions. Its members base their codenames after playing cards (usually Spades, but might use other card colours too). In its later incarnation, it became a franchise of sorts with several gangs of different members operating in several cities. The main members are; King, Queen, Jack and Ace, while at times there is also an additional one, under the alias of Ten.
- It was never really confirmed if there is any connection between the first and second iterations of the team. Moreover, the second iteration lacks a Jack. In the DC Comics, the first user of the "Jack" alias was the only surviving and active member of the original version of the gang.