By the end of "Arrow" season 3, the League of Assassins bowed down to their new leader — Malcolm Merlyn. More of the new Ra's Al Ghul will be seen in "Arrow" season 4 now that John Barrowman, the actor who portrays the character, has officially signed on as a series regular for the fourth run. 

Talking to the audience at the Las Vegas Comic-Con, Barrowman, who was particularly cautious not to reveal too much of what the new season holds, brought up the possibility of Laurel seeing her younger sister Sara — the resurrected version of the latter — in the new season.  

"I can't tell you anything, because I do know a bit of what's gonna happen," the actor said. "But if you love Malcolm Merlyn, if you love Oliver Queen, if you love Thea Queen, if you love the Canary sisters ... I say that with a bit of a twist and a joke, you're gonna love what's gonna happen across the DC world." 

He also added that the cast and crew will be back on set to shoot "Arrow" season 4 as early as next month. 

As fans of the DC small screen universe know, Sara will be reborn as the White Canary in the "Arrow/ The Flash" spin-off "Legends of Tomorrow" but nothing has been said when that will actually happen. With Barrowman's character becoming the Demon's Head, chances are he will be a big part of this. 

It is highly likely that before the spin-off debuts in January next year, "Arrow" season 4 will institute Sara's resurrection via the Lazarus Pit. However, it remains to be seen if Laurel, who took on the Black Canary moniker ever since Sara was killed by Malcolm, will get to see her younger sister once more. 

Ever since the deceased assassin's fate was revealed, questions about whether or not Laurel and Captain Lance will have an idea about it, and how the characters will be affected by it are constantly being raised. There's only one way to find out and that is waiting for "Arrow" season 4 premiere in fall.