Since Harley Quinn made a brief appearance in the latest episode of season 2 of 'Arrow,' speculation's running rife that the Batman villain will be making a more impactful comeback.
In a recent interview, Manu Bennett suggested that Slade's son might have other siblings, and asked fans to dig deeper for clues in the DC comics to appreciate that complexity of the storylines in 'Arrow.'
The promo photos of episode 15 of Season 2 of 'Arrow' show Roy and Slade with the Queen family. If this suggests some sort of coalition, it could pose as a threat to the Arrow team.