This article contains spoilers for the Arrow Season 6 episode 'Reversal'.
Tonight's Arrow was an interesting one in that it switched the roles of Felicity Smoak (Emily Bett Rickards) and Oliver Queen (Stephen Amell). Now that Oliver has given up the vigilante life, he's trying to do his job as mayor, raise his son and have a relationship — but Felicity is still part of the team and runs off when they need her. Last night, she got pulled back into the mess with Alena (Kacey Rohl) and Helix as we find out that Cayden James is trying to shut down the internet. Oh, and we see that Cayden James is in fact played by Michael Emerson.
While Felicity works to help Alena, the team is trying to figure out just why Black Siren (Katie Cassidy) is killing seemingly random people. Oliver, of course, can't help but follow Felicity and Alena, and takes out some bad guys because Felicity doesn't call the team in for backup. And we learn that those three dead are actually the key for James to get into the server room for the main hub for domain registrations (or something like that).
James, Black Siren, and his team go in and Team Arrow follows. There's fighting, computer talk, and Oliver ends up at the Bunker doing the computer thing as Felicity is in the field. Felicity saves the internet by getting past the firewall — which was all that James wanted in the first place, so he could put out certain code without there being an way to trace it back to him. And it ends with Oliver getting a phone call from an old friend (sort of).
The important thing in the episode is that we finally meet Cayden James. We see he is directly linked to Black Siren, having saved her from Lian Yu. He's also playing a long game — a game that will likely include Anatoly (David Nykl) and Ricardo Diaz (Kirk Acevedo). Though Oliver never officially suits up, we see that he is going to be struggling to leave that life behind. And Felicity finally knows the name for her company Helix Dynamics, that she will hire Alena in the future, and that they are going to try and mass produce the chip that allows her to walk again.
There weren't really many side plots this episode. The interaction between Oliver and Felicity was fun, especially seeing the roles reversed and how they both handled it.
Next week starts the two-part appearance of Deathstroke, AKA Slade Wilson (Manu Bennett). This may be one of the most anticipated stories since Bennett first returned for the season finale last year. The character has the Mirakuru out of his system and is sort of back to when he and Oliver were friends on Lian Yu — but he's still Slade. And he needs Oliver's help to find his son.
In the comic, Slade has three children — two follow in his footsteps as Ravager, while the third is the Titan named Jericho. We'll have to see what the showrunners have in mind for this one.