For Arrow executive producer Marc Guggenheim, very little has been sacred in the five years of the show: they've rewritten backstory from the ground up, turned the main character's mother into a mass murderer, killed off the Black Canary, and more. But, he told EW, there are two things that are beyond the pale.
One of the two -- and something he's said in the past -- is that Guggenheim doesn't want Felicity to suit up and go punch bad guys as a costumed vigilante. As viewers might imagine, then, the discussion came about in no small part because that's exactly what she did (albeit in an alternate timeline) on this week's episode of DC's Legends of Tomorrow.
In the sequence, Felicity plays a superheroed-up version of her Overwatch role from Team Arrow, albeit with a costume that's pretty reminiscent of The Huntress's from the comics. She's caught and killed by Sara Lance and Amaya Jiwe, who in this reality are working for Damien Darhk.
“We all recognized, ‘Well, who are we going to use from our Arrowverse?'” Guggenheim said of the sequence. “It’s always nice when you can pull in a character from one of the other shows. We talked about a lot of different ideas, and I said, ‘Since this is an alternate reality and we’ll probably never have the opportunity to do so again, I think it would be fun if we did Felicity as a superhero,’ because I’ve said it before, I’ll say it again: I have zero intention of ever putting Felicity in a mask and costume on Arrow. So this is really the only circumstance by which we could do it.”
The fandom is often split on the question of whether Felicity could or should ever suit up. On the face of it, it seems like the team hacker and Oliver's love interest is not the ideal candidate to become a superhero, and that suddenly being able to fight well enough to hold her own on Team Arrow strains credibility. The other side of that argument is that characters like Laurel Lance and Curtis Holt have trained themselves up to excellence in relatively short times, and weren't particularly discouraged from making the attempt by Oliver.
There's another school of thought that Felicity shouldn't be a superhero for the same reason other non-powered supporting characters shouldn't: because when everyone on a show is a costumed vigilante, there are dramatic elements that are lost because the main character or "team" never interacts with the people they're working to protect.
Guggenheim's second "never-do," though, will be welcome and a lot less controversial...
“There’s two lines in the sand that I’ve drawn for Arrow for myself,” Guggenheim elaborated. “I can’t speak for Greg [Berlanti] or for Wendy [Mericle], but for as long as I’m involved with the show, the two things I never want to do is kill off Thea [Willa Holland] and put Felicity in a mask and a costume. Those, to me, are two lines that I just think are a bridge too far. Thea, because we’ve taken so many family members away from Oliver, and Felicity because when you put a character like that in a costume, I think it diminishes who that character is and it makes the idea of superheroics seem silly.”