Warning: This article contains spoilers for SPIDER-MAN/DEADPOOL

In the past, putting Spider-Man and Deadpool together has been a kind of a light, funny affair. However, their relationship evolved a lot over the course of writer Joe Kelly and artist Ed McGuinness’ tenure on SPIDER-MAN/DEADPOOL, turning into a kind of emotionally fraught philosophical allegory—with butt jokes.

Kelly has worked on both characters extensively throughout his career, even writing their first team-up 20 years ago! As he concludes his current run with SPIDER-MAN/DEADPOOL #18—available now—we quizzed him on lessons learned this go around and bringing the story to a suitable close.

Marvel.com: I noticed that, in a previous interview you said that this was a dream project you couldn’t say no to. Has it lived up to that expectation?

Joe Kelly: Yeah, it definitely has. The whole team is really outstanding. Working with Ed is such a pleasure but everyone—[inker] Mark [Morales] and [colorist] Jason [Keith] and all the editors and everybody—it’s been a really, really wonderful experience. It definitely lived up to my hopes and expectations for sure. Deadpool’s the cornerstone of my career and Spider-Man has always been my favorite super hero, so it sort of felt like coming home.

Marvel.com: So, I did a little research and I found out that you and artist Pete Woods actually wrote the first instance of Spider-Man and Deadpool interacting in 1997! You guys were the ones to trail blaze that fan favorite pairing! Having worked with them before, do you have a set paradigm you stick to with Peter and Wade or did you set out to go somewhere new with them in this project?

Joe Kelly: It was definitely a combination. I mean, having done so much work with those characters and especially Deadpool, there are certain things that I feel like you almost have to do and explore. But it was really important to me to make sure I wasn’t just rehashing things that we had done before; I knew the readers wouldn’t want that. Like, it’s not 1997. I never want to go backwards, you know? But there’s so much territory to play around in with all both of those characters. Deadpool is so layered now—he’s a 20-year-old character! What was the most exciting for me, and especially worked out in the pitch, was this idea that Deadpool—despite his current popularity in the Marvel Universe—had still been a killer and Spidey just would not reconcile easily with that. [We wanted] to see how that relationship was gonna play out with the moral high ground for Spider-Man and the sort of fanboy bro crush side of Deadpool, and then to [shift] that [dynamic] over the course of the story. I’m glad I was able to go back to the well, and who [knows] what the future will hold? If enough people ask, I’m pretty weak-willed; I could be suckered into saying yes again.

Marvel.com: This series has gone into some more serious territory for both of the characters which is interesting because generally in the past when the duo have come together it’s been more light-hearted and funny. You guys dive into their relationship in a big way that we haven’t really seen before. How has it been going darker with the characters?

Joe Kelly: I think the expectation was that it was just going to be a light buddy book, and that absolutely works—there’s reasons to do that and it’s fun, and there’s no reason not to do [some of] that sort of stuff—but to get too caught up in that [would ignore the fascinating dynamic]. Deadpool’s disregard for the universe and life, etc., runs really deep whereas Spidey has this sense of [duty] to all of that same stuff and feels a literally cosmic level of responsibility and guilt so integral to his character. I feel like the universe is out to get both of them, in different ways and for different reasons. Some of that stuff they bring on themselves, which is either [because of] their poor choices or their blind spots.

Spider-Man/Deadpool #18 cover by Ed McGuinness

Marvel.com: Aside from the jokes and silliness, both of them do have pretty troubled pasts. It makes sense that they’d come together to help each other through that with their friendship…

Joe Kelly: Right, I wanted to see if that friendship could evolve and what would happen if it did. With Deadpool it’s about “Can he be the person he wants to be? Is that possible in [this] universe? Is he doomed to fail?” Especially having someone like Spider-Man at his side, that makes for a really volatile combination that you know is not going to be pretty over the course of time. It is gonna start out as fun and light, but these guys have too much going on and so to shy away from that stuff would have been a mistake. For me, that was the opportunity I got excited about. Spidey has confronted his dark side before, there’s no question, but [it’s different] to do it with Deadpool who loves him so much and wants to be him. Ultimately, there would be sacrifices made [for both of them.] When we finally get to the end of the Itsy arc, you’re definitely getting a sense of [what each will choose] when they’re really boxed in…[but] it’s always about choice.

Marvel.com: People find common ground between them because of the comedy element and the costuming, but they’re actually pretty different philosophically. I wanted to ask you how they’ve been rubbing off on each other—literally, figuratively, and even narratively?

Joe Kelly: I think that the first arc where Spidey acknowledged that they were friends was when you could see them trading off some stuff. Not the dark stuff, but Spidey being willing to cut loose in the Thor issue and live life in a little more of a goofy way, and then Deadpool really trying to step up his game—even with the Mercs for Money issue where he’s saying “What we’re doing isn’t great but the world’s more complex than that”—having those counterpoints is what you want to see as [they’re] becoming friends. But then a question that is raised is can people change?

Deadpool aspires to be [something new] because he knows that the reasons people love [him as a hero] are false. Deadpool knows that, in his heart, he’s not the greatest guy on the planet. And Spidey really is this pure soul, but he gets pushed and pushed and pushed…will he break?

If Spidey was left alone, would he have killed Itsy Bitsy? Maybe. I mean, it’s possible, if Deadpool wasn’t there. And if Spidey hadn’t gone so far down the road with Itsy Bitsy, then would Deadpool have had to make that sacrifice and take a life, which, in our universe, he hadn’t been doing for a while. So for him to have to cross that line again morally…does that mean [Wade] couldn’t really change, even if he wanted to? The answers for both of them are left sort of ambiguous.

Hopefully whoever comes on after it will run with those themes and that’s the most interesting thing about these guys. Like you said, on the surface there’s a lot of reflections. [Deadpool character creator Rob Liefeld] has openly said many times that he wanted to do “Spider-Man with guns” and that was part of the Deadpool creation. But they’re very distinct [from one another now] and you want to make sure you’re giving them their due.

Pick up SPIDER-MAN/DEADPOOL #18 to catch the end of Joe Kelly and Ed McGuinness’ run, available now!