Dean and Sam may have decades of experience as hunters under their belt, but they’ll have to learn the ropes all over again in Tuesday’s debut of the potential spin-off Supernatural: Bloodlines (The CW, 9/8c).

When the brothers arrive in Chicago, they’ll discover that five Mafia-esque monster families rule the metropolis, leaving hunters — like newly minted creature killer Ennis (played by Episodes‘ Lucien Laviscount) — without the upper hand and unable to use their usual tricks.

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But that’s not the only difference between Bloodlines and its mothership series. Below, writer Andrew Dabb discusses the offshoot’s relationship-driven storytelling, more “human” monsters and complicated romantic entanglements.

Dabb also reveals whether the Winchesters will be paying a return visit to the Windy City.

TVLINE | Let’s start with Bloodlines‘ origins: Did you pitch the idea? Was it something that started in the writers room? Or did it come from the network?

We always knew, from both the network and the studio, that there was a real interest in doing a Supernatural spin-off. But for us, internally, a) It’s been so good for so long, and b) It’s going into Season 10 – and we all very much hope it’s going to go beyond Season 10. You don’t want to do another show that’s just about hunters because then you’re competing with Supernatural. So it really was a conversation between myself, [series creator] Eric Kripke and [executive producers] Bob Singer and Jeremy Carver about what can we do to make it in the world of Supernatural, but not an exact clone of Supernatural.

Sam and Dean roll into town in wherever, Missouri, and flash a badge and say they’re agents and no one really bats an eye. But if you did that in the city, more than once with different aliases, people are going to notice. So hunters have to function differently in the city. Then we thought, “How would monsters function in the city?” We got the idea that if you’re in a city with 3 million people and you’re a monster, you don’t really need to leave. You can kill a lot of people and no one would really notice. So if you stay, you’re starting a family [and] then it could grow from there and that led us to talk about the mob and five families.

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TVLINE | It sounds like monsters have the advantage in the city versus hunters in rural Americana.

We’ve got some monster families that have been there since the city was founded. Some of them are part of the city not only as the criminal side, but the legit side. They’re big donors. They’re involved in politics [and] higher echelon. So a hunter is at a disadvantage when he starts out in Chicago. We’ll see that a little bit with Sam and Dean, and we’ll see that very much with Ennis if the show goes forward. … The truth of the matter is, monsters are afraid of hunters. Our monster mob families have really tried to keep a low profile. Any hunter that manages to stumble in and figure out what’s going on, they have a lot of incentive to get rid of that person because it creates real problems for them. It is something where the scales are tipped a little more in the monsters’ favor, but that just makes the hunters more heroic for standing up to them.

TVLINE | Your monsters are ruling Chicago. Vampires control New Orleans on The Originals. You need to team up and just take over the world and The CW.

I feel there’s too much angst. That would be the real problem. There’s too much staring into mirrors and shedding single tears to really take over the world. But that’s something we want to have fun with in Bloodlines — building it out more. In the pilot, there’s a reference to how things are in New York. The idea is that there’s this other world we haven’t explored on Supernatural proper that we could really have some fun with.

TVLINE | You have werewolves and shapeshifters. What are the other monster families ruling Chicago?

We’ll meet, in the pilot, Djinn. And Ghouls are the fourth family and then our fifth family, which is actually an all-female family, is sirens.

TVLINE | You chose not to include vampires. Is there a reason for that? Are there just too many vampires on the network already?

I think vampires will play into the show. We looked at how vampires are handled in Supernatural proper. Outside of our Alpha vampire, vampires on our show are always truckers or drunks or bikers. They’re really down and dirty and blue collar. When we see them in Bloodlines, they will be the same. So we will have them, but we’re going to explore them in a different way that makes it a little more gritty.

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TVLINE | How are Sam and Dean introduced to this world?

Sam and Dean come into Chicago very much the same way they come into any case, which is there’s a death that draws them in. The deeper they get, [the more] they realize this is bigger than they had anticipated. Ultimately, they realize, “Holy crap, this is an entire city run by monsters.”

TVLINE | Generally speaking, Sam and Dean are against monsters. What’s their reaction when they find themselves in this turf war?

Sam and Dean are against monsters, although in recent seasons, we’ve really tried to soften that a little bit. They’ve met a bunch of monsters who are fairly sympathetic. That’s what they’re looking at here because they’re meeting monsters who are bad guys, definitely. But they’re also meeting monsters who are sympathetic and want the best and aren’t looking to kill people. It’s very important for us — because all but two of our characters are monsters on this show — to present monsters who may not be human, but they’ve got humanity. You understand where they’re coming from. They are people. Sam and Dean are drawn into this world, and they’re kind of shocked by it. They had no idea it could go this far. But at the same time, their philosophy is not, “Burn it all down,” because that’s not really where they are now.

TVLINE | Looking at the promo photos, I was really struck by how many characters there are. Would you say that makes Bloodlines a more relationship-driven show than Supernatural, which, despite having a serialized mythology, is very a monster-of-the-week show?

Yeah, Bloodlines was always conceived as an ensemble show. It’s going to be a more serialized show. It’s going to be a more relationship-oriented show. That doesn’t mean we’re not going to have fun kills and action and people getting their heads chopped off, because this is Supernatural and that’s what we do. But yes, it’s not going to be a case-of-the-week show. Supernatural does that so well and has done it so well for so long, I’m not sure you want to cannibalize that.

TVLINE | Another difference: there’s a dash of romance. Can you talk about the relationship between David (The Originals’ Nathaniel Bozulic) and Violet (Melissa Roxburgh)?

We’ve got six incredibly great actors. You get them all together, things are going to happen. But the core relationship to begin with is the David and Violet relationship. We would like to think it’s a little bit of a twist on the standard Romeo and Juliet thing. She’s a werewolf, he’s a shapeshifter. But the idea is they had a relationship three years ago. It ended in a very bad way, so when they get together again three years later in our pilot, it’s not like people fawning in love. It’s not young puppy love. It’s much more, “You burned me, I burned you. We still like each other, but can we get back into this?”

TVLINE | If Bloodlines goes to series, what kind of lasting impact will Sam and Dean’s presence in Chicago have?

Sam and Dean being here is really what starts Ennis, our hunter character, off and gets our monster families revved up. Sam and Dean being here is the first domino to fall that makes the series possible. It’s incredibly important. They’ve got their own show to go to, and it’s a great show. But should Bloodlines go forward, we’d love to have them back if things worked out scheduling-wise and if we could find a story that’s cool and doesn’t feel like a repeat of the planted pilot.