"The city is in danger, it must be May." – that was the rather self-aware line delivered by Quentin Lance (Paul Blackthorne) in the season three finale of Arrow. In the first three seasons the shows tone has been dark and building to a cataclysmic event… destruction of Starling City by Malcolm Merlyn (John Barrowman), Wade Wilson (Manu Bennett) and Ra's al Ghul (Matt Nable). Now the big bad motif won't be changing as we'll get to meet Damien Darhk, but the tone of the show will be a bit lighter with season four as executive producer Marc Guggenheim told io9.com.
It will take a lighter tone. That's pretty much the only thing I say without spoiling it. We've been working for about a month now in the writers' room, talking about Season Four, and I think that one thing we all collectively understood was Season Three beginning with Sara's death, because it's the death of a major character on the show, it set a tone for the remainder of the season. And I'm not the least bit apologetic for that tone. I happen to like dark and I like the fact that Arrow is a pretty dark show particularly for a network show. That said, every year you want to mix things up and there was sort of a collective desire on all of our parts to try to inject a little bit more lightness into the show, a little bit more humor. It's not going to radically change. The show's still going to be the show but in terms of tone we're coming off a very very hard season for all of our characters. We wanted to try to mix it up a little bit.
With the Flash succeeding with a much lighter tone and DC's Legends of Tomorrow also appearing to be lighter… keeping Arrow dark to be different but turning it down a little will make the crossing over a little easier in the long run.