After three years and countless songs about heavy boobs, first penises and mental health diagnoses, The CW’s Crazy Ex-Girlfriend begins its fourth and final season Friday. The show's subversive tone and ear-worm-y tunes have cultivated a voracious fan base that managed to keep the series afloat despite its relatively small overall size.

The Hollywood Reporter spoke with showrunner Aline Brosh McKenna, who co-created the series with Rachel Bloom, about crafting the show’s tone, the recasting of Greg with Skylar Astin, telling complicated female stories, working alongside other female showrunners and comparisons between Rebecca Bunch and Breaking Bad’s Walter White.

Heading into the final season, how does it feel to be able to end the show on your and Rachel’s terms?

I mean, a lot of our experience has been a rarity, because we're so fully supported by The CW and have been from the beginning. We told them that it was a four-season show, and our ratings have been so poor it's amazing that we got more than one season at all. To be granted the privilege of doing all four chapters of this story? We're grateful every day. If it wasn't for the critics and the Golden Globe and the passion of the fan base, this show would not still be airing.

Rebecca Bunch is dealing with issues we’ve not often seen tackled in any light, let alone a humorous one. Did you have guidelines for handling that?

It's funny: Rachel and I have very different backgrounds — there are areas of experience and knowledge that we each have that are completely different. Rachel comes from musical theater, sketch and animation, and I come from writing pretty traditional movies, so there were a lot of areas where our sensibilities overlapped and a lot of places where our sensibilities were completely different, and that's great. I think some people, when they collaborate, they're sort of one brain and finish each other's sentences. Rachel and I have that sometimes, but often our partnership brings a completely different point of view to the table, and I really treasure that, because she thinks the things I would never think of and has a point of view that I don't have, and vice versa. That's been one of the real joys of the show, finding that blend of our tones.

Do you think there is a different style, or something new, brought to the table with female showrunners?

I've worked for people who seemed like they were miserable and didn't want to go home to their wives and children. And so I think our hours are, honestly, one of the things that distinguishes us in a gendered way. It’s very important to us that the writers have lives so they have something to write about, and I don't really know any other way. Ours is an industry that can be not conducive to a family life, so for us it was important to preserve that for people.

As a screenwriter, it's very frustrating because you never have the final say on anything. So with this job — while it’s much, much more time-consuming than being a screenwriter — it has been kind of relaxing because there's something very freeing about knowing whatever mistakes you make, they're yours.

The show has aired in a period of time where we've seen a lot of change in terms of what we're seeing on TV. What has that been like for you?

The biggest change by far has been the kind of female characters that are “allowed” on television. My whole career has been a struggle to get female characters that are dimensional and flawed and not, you know, just thoroughly “adorable” on television and in movies. It's really been a struggle, but things have really changed. If you look at the TV landscape in terms of lead characters? I think Lena Dunham and Tina Fey really blazed the trail in the half-hour comedy space, and now you look around and you see Insecure and Fleabag and Catastrophe — there's just so many shows now where the female leads are complicated and dimensional and interesting and flawed and all the things that men had been allowed to be.

Have you talked to many of the other female showrunners out there? Have you ever had a chance to get together and chat?

Yeah, there's been some get-togethers and there's definitely a little community here. I have a lot of friends who are female showrunners, so I have a lot of people to call and ask for advice — particularly since we're on The CW. When we started, I cold-called Jennie Urman from Jane the Virgin, and she has been enormously helpful to me.

The medium just lends itself to more collaboration, I imagine.

[With movies], you’re very aware that it's one and done, that we're going to come in and have this experience, and then go our separate ways. [In TV], there’s a much longer unfurling of these relationships and a much longer collaboration, so there's this sense that you have to protect those relationships, because they have to go on and on for months. We have many people here who have been with the show since the pilot.

I really relate it to The Great British Baking Show, you know? You stick the ingredients in the oven and hope for the best, and every time you try to figure out how to do it differently. But there's an element of serendipity, for good and for bad. It's a wonderful process of making things and then seeing how they come out and then dealing with what you got.

What are the biggest challenges to portraying Rebecca’s mental health onscreen?

One of the real joys of the show is that it is a first-person perspective show; we’re always seeing things from Rebecca’s skewed POV, which is why you find out things like [the revelation that] Mrs. Hernandez had always been speaking, Rebecca just never noticed. So the idea that Greg [now played by Skylar Astin, previously by Santino Fontana] seems so completely different to her that he actually looks like a different person, is very much in keeping with what we know about her. That's where the songs come from as well.

I read at one point that you said that Breaking Bad was a huge reference point for Crazy Ex-Girlfriend. How does that play into the final season?

The slow evolution of a character. In Breaking Bad, it's an evolution downward. For us, it's the unraveling and re-routing of the character, so Walt’s descent into evil, in some ways, mirrors Rebecca's descent into being unspooled. This, however, is the season where she starts to put the pieces of herself back together. But in typical Rebecca Bunch fashion, it's a bit wrong-headed.