Spoilers follow for recent episodes of Arrow.
This week's episode of Arrow saw a bomb dropped with the surprise death of Moira Queen, played by Susanna Thompson. At the end of the episode, just as Moira was about to reveal a secret about Malcolm Merlyn to Oliver and Thea, their limo was blind-sided by Slade, who captured them.
As seen in previous episodes with various flashback scenes, Oliver Queen was forced to choose between Shado and Sara. Well, Slade did the same with Moira and Thea; however, Oliver didn't get a chance to choose as Moira volunteered. Slade then remarked she has great courage, but didn't pass it on to Oliver. He then stabbed her with his sword, killing Moira.
Arrow EP Andrew Kreisberg explained the death of Moira to CBR:
I don't want to give the impression that we sort of [said], "Well, somebody has to die, let's spin the wheel. Bad luck, Moira."
It really was, just like with Tommy, "Where is her trajectory going?" In season one, she has this incredible secret, that she was part of The Undertaking. She suffered for it, and went to jail for it, and then we discovered she had an even better secret -- that Thea is really the daughter of Malcolm Merlyn. When that secret blew up, it split the whole family apart. Obviously, we've been taking steps to bring people back together again, and knowing it was only going to be powerful if Slade really changed the game by doing something truly monstrous, it was, "Well, if Moira wins the mayorship, if she makes up with her kids, what is she?" What is Moira without a giant secret? And if they all forgive her, and then there's some other giant secret, for us it sort of felt like we were becoming a soap opera.
In a way, she could die a hero's death, and also die this person who was conflicted, because even as she's saying, "Hey, we have to tell the truth," we're seeing that she's kept this other horrible secret. You just literally can't change her, despite the fact that she sacrifices herself for her children -- which is so amazing, yet she was still lying. We felt like ending it at this time left you with that great feeling of what an amazing character she was, rather than let her become a caricature. That was the math, and just like Tommy, it was horrible math, and it was tearful math, but her death, just like with Tommy, has a profound impact on everyone on this series. It's certainly what's going to drive Oliver in these last three episodes, and it's going to drive Thea, not only in these last three episodes, but also into season three.
As Kreisberg mentions above, Thea is the daughter of Malcolm Merlyn, aka the Dark Archer and member of the League Of Assassins. Merlyn is set to return in the final two episodes this season, and if the meme Stephen Amell posted on his Facebook is anything to go by, Merlyn isn't too happy.
Especially with Deathstroke.
Here's the episode description for "Streets Of Fire" that sees John Barrowman return, which is set to air May 7th on the CW.
MALCOLM MERLYN RETURNS — Oliver (Stephen Amell) rallies his team as Slade’s (Manu Bennett) soldiers attack the city. Felicity (Emily Bett Rickards) gets a call from S.T.A.R. Labs with game-changing news and Thea (Willa Holland) comes face-to-face with her father – Malcolm Merlyn (guest star John Barrowman). Nick Copus directed the episode written by Jake Coburn & Ben Sokolowski (#222).