Oliver Queen will return to Starling City but what could be the reason? Earlier "Arrow" season 4 spoiler said it has something to do with his sister Thea (Willa Holland).
The younger Queen had his costume last season and she might be seen next season acting as vigilante alongside other members of Team Arrow. While Thea is a good addition to the team, she might not be enough. Oliver will be forced to return to his beloved city because the new enemy is a force to reckon with.
Damie Darhk has been publicly advertised as the big bad of "Arrow." He will be played by "Justice" star Neal McDonough and according to recent press release, Darhk is more ruthless than last season's villain Ra's al Ghul (portrayed by Matt Nable).
Now, in a new "Arrow" season 4 spoiler from Entertainment Weekly, fans need to brace themselves as Damien Darhk is revealed to be a "pure villain" unlike the ones who are only cruel for the greater good. Co-executive producer Marc Guggenheim even revealed him as the "Prince of Darkness." EW wrote quoting Guggenheim.
"[Oliver] left the city in very good hands," EP Marc Guggenheim tells me. "He entrusted Laurel, Diggle and Thea to mind the fort. Damien represents a threat that three heroes are not enough to combat. When we've written the villains - the big bads of the season - we always took the approach that they were heroes of their own story. They were doing the wrong thing for what they consider the right things. That's not the case with Damien. He's not nearly as moral. We wanted a villain who was pure evil because we've never really done that on the show before. That's what Damien represents. He's the prince of darkness."
Oliver's abrupt return to the city is definitely a must as Darhk is not the only they will battle. Most recent "Arrow" season 4 spoiler said Anarky is set to join the show and will be portrayed by Alexander Calvert.
"Lonnie Machin (AKA Anarky) is a deranged freelancing criminal who is willing to do whatever it takes to impress a potential employer," Comic Book Resources described in its "Arrow" season 4 spoiler.