What happens when someone like Black Siren teams up with one of the most dangerous hackers on Arrow? That is the major question on Arrow Season 6 Episode 4.

Arrow managed to surprise me big time with the reveal of who saved Laurel on Lian Yu. I was convinced this whole time that it was going to be Ricardo Diaz (who is showing up soon!), but I was dead wrong.

It didn't shock me that Michael Emerson was playing Cayden James. However, that didn't make Emerson's entrance in Arrow Season 6 less enjoyable. If he hadn't been Cayden, I couldn't picture who else Emerson could have been playing.

Helix was a mixed bag for me during Arrow Season 5 with its ups and many downs. But the introduction of Cayden sparked my interest again. I'm mostly intrigued by the idea that he and Laurel are teaming up.

Although they better explain how Cayden 1) knew about Black Siren, 2) knew where she was, and 3) how he helped her. I will admit that the whole "virus that will kill 300 million people" went over my head.

When it comes to Arrow's ability to sell hacker problems, I mostly nod and smile. While I may not always take it seriously, I did enjoy the story it gave for Felicity.

It was honestly my favorite Felicity-centric hour in a very long time. Despite Cayden's plan being what it was, I enjoyed Felicity's role in all of it because it let her take part of the larger team action.

The role-swapping between Felicity and Oliver ended up being one of the better parts of "Reversal." Even though I want Oliver back as the Green Arrow already, the role reversal were fun.

My issue with Felicity throughout the last few seasons is how she been utilized. Either she is restricted to being a love interest or she goes down a dark path as she did on Arrow Season 5.

But here I could feel that there was a solid balance. Her romance with Oliver didn't restrict her to being only Oliver's girlfriend. "Reversal" managed to let her be multiple roles and that is the Felicity I personally dig.

As I mentioned in the review for Arrow Season 6 Episode 3, I'm cautiously optimistic that Arrow won't overdo the Oliver/Felicity romance. "Reversal" helped me keep that optimism. There was never a point when I rolled my eyes about their romance.

If they can continue with this exact dose, then I won't have any problems. As I said, this became one of my favorite outings of Felicity's as a character which I never thought would happen.

Speaking of highlights, let's talk some Black Siren. As a comic book fan, I geeked out like crazy when she said "Call me Dinah" for so many reasons. I never thought any version of Laurel would ever get to say that.

I'll admit that I'm mixed about her ability to kill people so easily. On the one hand, it's genuinely messed up to see any Laurel killing someone without hesitation. But if you look deeper, it's a compelling story that has yet to be told.

This Laurel is obviously getting further into her downward spiral after what she went through on Earth-2. I don't believe she is a Laurel who was simply born evil. This Laurel even implied that she lost most of her family.

Hearing her talk about how she had a family once makes me wish that those Earth-2 flashbacks are coming. I desperately want to see what her life looked like in that other universe. Even though her killing spree is intense, there is a deeper story there.

As to whether or not she can be redeemed, that's a different story. But overall, I enjoyed what we saw of Black Siren and those small subtle nods are hinting that it's not as black and white as some may think.

If there is anything that didn't work in "Reversal," it was Oliver. Not that he did anything wrong, but he simply didn't have anything to do. I enjoyed the moments where he was supporting Felicity in the apartment and the bunker.

But other than that...what did the show's main character have to do? That is right now the only weakness of the Diggle-As-Green-Arrow storyline. It doesn't give Oliver anything worthwhile to do.

We barely saw him as the mayor because he decided to risk putting on a mask again to save Felicity. I appreciate the fact that she called him out on it because he is being reckless.

But it does look like Arrow Season 6 Episode 5 will give our not-costumed-man plenty to do. Especially after the phone call he got, even though I wish they could have gotten Manu Bennett for that call.

Overall, "Reversal" was an incredibly enjoyable episode particularly for Felicity as well as Black Siren. While Cayden's big hack plan may be over my head, Emerson's portrayal of the role is delicious to watch. Now it's your turn to let us know what you thought of Arrow Season 6 Episode 4!