Ever since the DC Universe exploded onto The CW with the introduction of "Arrow" in 2012, writer/producer Marc Guggenheim has been one of the prime architects translating both long-standing and fresh comic book mythology into TV stories.

Now, whenever Guggenheim, a frequent comic book writer himself, offers up a preview of what's ahead for the two series he's currently guiding, "Arrow" and "Legends of Tomorrow" -- plus a tidbit or two on that upcoming crossover that includes "The Flash" and "Supergirl" -- one thing becomes clear: every time one of the series turns over a big new reveal, there's even more big things to come with each revelation.

"Arrow"

On Ragman Rory Reagan's reaction to knowledge Felicity was responsible for the destruction in Havenrock:

I feel like he's got a very human reaction. He reacts to it the way I think you might expect him to, but not in an overblown way. I think it's very grounded and very human.

We talked a lot about that storyline, and Rory's point of view and Felicity's point of view. I will say that a lot of times, you write something and you do a storyline and it has a very different reaction than the one you expected. I think we were all taken aback, not in a bad way but just surprised, that there was so much outrage over Felicity's actions in Episode 421. People were upset at Felicity, somehow, for saving Monument Point, at the expense of Havenrock.

It was fun to actually get a chance to articulate the anti-Felicity point of view, and the pro-Felicity point of view. It made for a very interesting moral dilemma, and we had a chance to play with that.

On whether Diggle and Lyla will become aware of the changes to their family as a result of "Flashpoint":

I always say that, on "Arrow," there is no secret that doesn't eventually get discovered.

On how the story of newly introduced D.A. Adrian Chase, who becomes the superhero Vigilante in the comic books, will move forward:

Episode 507 is where we show our cards the most, in terms of Adrian. What's fun about the way we're writing and portraying Adrian is that we're writing with a certain amount of comic book knowledge. And if you're not a comic book fan, it will just fly over your head and that's totally fine. It's like an adult joke in a Pixar movie.

But if you are familiar with the comic, you'll probably interpret certain scenes in a very specific way, and that's fun for us. I don't think we've ever really used their comic book trajectory and destiny, in this fashion, before, as part of the storytelling.

On Quentin Lance's path as he attempts to recover from alcoholism while serving as Oliver's Deputy Mayor:

It's definitely not an easy one. Thea's decision to make him Deputy Mayor is very noble on Thea's part, but it's also very naive, given the amount of demons that Quentin is wrestling with. It's not going to be as simple as just having a new job title. It's going to get a lot harder before it gets easier. It's Arrow, so that probably stands to reason.

On when the briefly glimpsed Prometheus will return as a more direct threat to Team Arrow:

Episode 506 is when things really start to kick into a higher gear. It's a 23 episode season. This is true for all the shows, especially when you have a big bad that's introduced in the first episode, but you have to strike a balance between it becoming the Prometheus show and becoming very repetitive, and teasing it out. Episode 506 felt right to us because 505 felt like the end of a chapter, and then 506 kicks things into another gear.

On when Felicity's still-secret romance will come to light:

It's the classic thing of "no secrets stay a secret forever" on Arrow. Oliver is going to find out about Felicity's boyfriend in Episode 505. Because, I'm spoiling that, I'm not going to spoil when Felicity's boyfriend finds out that Felicity is working with Arrow.

On how Curtis Holt still has some training to do before claiming the title of Mr. Terrific:

I think he's still got a ways to go on his journey. For one thing, that's not the final costume. We decided to give some of the recruits what we call "proto costumes." They have to earn the final one.

In terms of all of these characters becoming or being vigilantes, Curtis has the furthest to go. The evolution of Curtis, from comic relief and sidekick to butt-kicking superhero, is a big throw, in my opinion. The only way to do it properly is to watch him try, and then watch him fail, and watch him fail, and watch him fail. So, it's going to be a real struggle for him, as we go through the fifth season.

One the challenge of having "Arrow's" landmark 100th episode fall within the four-series fall crossover while still retaining its own distinction:

The challenge was that we've only got 42 minutes, and it's the middle part of a three-part story. At the same time, it's the 100th episode. When the news broke that the 100th episode was also going to be the cross-over episode, people were up and down my Twitter and Greg [Berlanti]'s Twitter. In a very positive way, people didn't want to feel like the cross-over was hijacking what should be a really seminal episode and moment for Arrow, which is wonderful.

I don't want to spoil it, but Greg came up with an idea that really does allow us to have our cake and eat it too. I haven't seen the episode all cut together yet, but it has some incredibly iconic moments. It is a love letter to the show. It draws on all previous 99 episodes. Everyone who we could have in the episode, from a scheduling point of view, is in the episode. Even the people who we couldn't have because of having conflicting schedules are represented. At the same time, you've got The Flash and Supergirl, and that's an enormous amount of fun. The recruits also play a very large and important role in the episode.

I'm really excited about it. There's one moment in it that I think is probably Stephen Amell's finest performance to date. This one scene, that really has two moments within the one scene, will just break your heart. It will take your heart, pull it out, and stomp it on the floor. It's very, very affecting, and it's all on Stephen's back. It's incredible. Willa [Holland] is amazing in the episode.

Everyone obviously brought their A-game to it. I'm really, really excited about it. It's the 100th episode!

"Legends of Tomorrow"

On how the JSA stays involved, without the Legends having to return again and again to 1942:

I don't want to spoil too much. I will say that we do go back to 1987 and we'll meet a much older version of Obsidian, who is going to be played by Lance Henriksen. That's one way.

And then we have another device up our sleeves that I don't want to spoil because it deals with stuff that is mythology-based in the back half of the year.

On how Vixen will stay very much in the picture going forward:

We'll deal with it very directly in Episode 203. We pick up 203, facing that issue head-on. You have a clue to it in Rex's final words to her. If you're Vixen and you've got Rex Tyler dying in your arms and you hear the words "time traveler," who would you think is responsible?

On the search for the time-lost Rip Hunter:

That's going to be something that's always going on in the background -- and in some cases the foreground -- of various episodes, to a certain extent. We don't want to change the mission statement from fixing aberrations to going and saving Rip, but the bat has been taken out of their hands, in the sense that there's no way to find Rip, so what can they do?

Even if they said that priority number one was finding Rip, I don't know how they would go about it, given the nature of Rip's disappearance.

[The audience] will find out before the Legends do.

On the nature of Nate Heywood's forthcoming superpowers:

One of the reasons why we wanted to bring the character of Nate into the show was that we wanted to play with something that "The Flash" got the chance to really play with in Season 1, which is the fun of telling an origin story for a hero.

In the evolution of a hero, there are all these fun seminal moments that we wanted to put our own Legends spin on. Part of that is discovering you have powers, part of it is learning how to control those powers, and part of it is the first time you go out in costume, part of it is the first time you fail, and part of it is the first time you realize you have a weakness.

We want to be able to tell all those different kinds of stories. You can safely assume the reason we brought in Nate was so that we could tell those kinds of stories, including the unpredictable nature of his powers. The next episode, 203, really shows how difficult it is for Nate to get his powers under control.

On when the members of the Legion of Doom start reappearing:

You'll see John Barrowman as Malcolm Merlyn in "Legends" Episode 208. You'll also see John in "Arrow" Episode 508, which is the 100th episode. You'll see Neal McDonough back as Damien Darhk in the 100th episode. You'll see Wentworth Miller back as Captain Cold in the "Legends" mid-season finale, which is Episode 208.

On the White Canary's new leadership role:

It's funny: you come up with character journeys for the season and sometimes they work out better than you ever expected, like with Sara -- and there are other times that are worse than you ever expected, like with Kendra and Ray.

I will say that I've gotta give a lot of props to Caity Lotz. As you start to see her become more and more comfortable with being the leader of this rag-tag group, it's so much fun to watch her. The character is embodying the role of leader, and Caity's performance really embraces it. It turns out to be one of the most successful things that we've done in Season 2. I'm super excited about it.

The Crossover

On telling the crossover story in a prelude and three parts across all four DC Universe series:

There's going to be an episode of "Supergirl" that ends with Supergirl going over to the crossover. Some people call it a four-way crossover because it involves four shows. My ulcer requires me to call it a three-part crossover. The story that's being told has a beginning, middle, and end. It's a beginning in "The Flash," a middle in "Arrow," and an end in "Legends," but "Supergirl" is very much a part of the whole thing.

"Arrow" airs Wednesdays and "Legends of Tomorrow" airs Thursdays on The CW.