The previous episode of "Arrow" was full of twists, one prompting Roy Harper a.k.a. Arsenal's departure from Starling City, which now thinks he's dead. But the person who actually met their demise was the love of his life, Thea, after Ra's Al Ghul killed her the same way Slade Wilson killed her mother, Moira. 

The "Arrow" installment titled "The Fallen" marks the first showing of the infamous Lazarus Pit in the series, the waters that can bring back the dead or make one immortal. Ra's himself takes a dip in those powerful waters to keep himself alive for as long as he wishes. 

The promo for episode 20 shows Team Arrow along with Malcome Merlyn in Nanda Parbat, with Oliver carrying Thea in his arms. The hero is left with no choice but to take his sister there to see her alive again. However, the price that comes with such a big favor is hefty — as hefty as being the next Ra's Al Ghul. 

Oliver is not one to lose another person he cares about, and accepting the demon's head's offer after resisting so strongly may just be the only thing that could bring his sister back to life and altogether stop Ra's body count from mounting. 

However, this may be when "Arrow" fans will begin to see a new Thea. In the promo for the episode, Malcolm tells Oliver that the waters change the soul of the people who use it, and even he could not imagine seeing his daughter alive but different. 

In one scene, Malcolm tells a lifeless Thea that she can already leave if she does not want to return, primarily because he is too afraid to see Thea's old soul be changed to a new and possibly a sinister one. However, many believe that Thea's resurrection will also mark her inclusion in Team Arrow. 

"Arrow" season 3 episode 20 "The Fallen" will air on April 22.