'Arrow' season 5 spoilers, news: Stephen Arnell hints major character's return; more details about Prometheus to be revealed

Following the unexpected death and major plot twist in the season 5 fall finale, "Arrow" will explore the possible return of a fan-favorite character when the series returns next year.

In the fall finale titled "What We Leave Behind," Oliver (Stephen Arnell) became more determined to track Prometheus when he discovered clues tied to his past as The Hood. However, just when he thought he finally found and killed Prometheus, Oliver quickly realized that he was fooled and that inside the mask/costume was a gagged Det. Billy Malone (guest star Tyler Ritter), Felicity's (Emily Bett Rickards) new boyfriend. At the end of the episode, Oliver comes back to the lair and comes face to face with a seemingly alive Laurel Lance (Katie Cassidy) who greets him.

During a Facebook Live chat, Arnell told fans that they haven't seen the last of Laurel when she made her surprise appearance in episode 9. "Is Laurel really alive? I guess we'll have to tune in [next episode]," the actor said. "People don't just come back from the dead. Obviously there will be some sort of vetting process [to determine if it's really her]. We delve into that when we come back in the New Year," he added.

According to Arnell, the script for episode 10 "legitimately freaked" him out, adding that the plot for the next few episodes "is a very cool development" because it "certainly raises the stakes for Mr. Prometheus."

Details on Laurel's appearance in future episodes are still being kept under wraps, but as per IMDB, Cassidy will still be on the show until 2017. One of the most notable characters in the "Arrow"-verse, Laurel was killed off by Damien Dahrk in the season 4 episode titled "Eleven-Fifty-Nine." At the time, it was said that she was certainly dead, and the series won't be using its usual tricks to bring the character back.

The fifth season of "Arrow" returns on Wednesday, Jan. 25, at 8 p.m. ET on The CW.