Oliver and co. will have a lot on their plate in season 6 of Arrow, including an FBI investigation into Oliver's activities, the return of Vigilante, and the search for Slade Wilson's son, Joe. In the season 5 finale, Oliver had his final showdown with the season's big bad, Prometheus. Instead of defeating the villain in traditional superhero fashion, Oliver wasn't able to keep Prometheus from getting what he wanted.
Prometheus triggered an explosion on the island of Lian Yu. Though the explosion won't mean the death of every character on the island, it is expected to have long-lasting consequences, which will somehow force Oliver to raise his son. The battle at Lian Yu also allowed for the return of the main villain from season 2, Deathstroke. In exchange for Deathstroke's help against Prometheus, Oliver promised to help him find his own son.
TVLine has revealed many spoilers for what lies ahead for Team Arrow in season 6. Oliver will be in "hot water" as FBI agent Samandra Watson (Sydelle Noel) is going to get dangerous close to finding out his secret. Co-showrunner Wendy Mericle confirmed that the season 5 villain Vigilante will finally be unmasked to reveal a "very personal" connection to a member of Team Arrow.
Mericle also teased an "amazing story" that will show Oliver keeping his word and helping Slade find his son. The story will also tie in with Oliver's situation with his own son. It's possible that this storyline will play out during the flashback-heavy, two-part episode that will center on Deathstroke.
Deathstroke's son, Joe Wilson, was previously believed dead until Oliver mentioned that he was still alive. Joe has yet to make an appearance in the Arrowverse, but has been an established character in the comic books since 1984. Known as Jericho, Joe was a member of the Teen Titans. As a child, the character was left mute after a violent encounter with one of his father's enemies. Joe later developed a superpower that allowed him to mentally control others via eye contact. Joe's powers eventually led to periods of insanity, causing the character to become an anti-hero and occasional villain.
There is no news yet on who will play Joe, but there have been reports The CW was looking to cast an Australian teenager. Another of Deathstroke's sons, Grant, appeared as Deathstroke's successor in an alternate future on Legends of Tomorrow. It's unclear if Grant's existence will be acknowledged by Slade in Arrow.
Season 6 of Arrow premieres Thursday, October 12, on The CW.