When The Secret Life of Pets was released this summer, no one quite expected it to be the juggernaut it became, earning nearly $900 million at the box office. Then again, who wouldn't relate to a movie about pets and what they do when their owners are gone?

The story follows Max (Louis C.K.), a spoiled terrier who doesn’t like his owner’s new adoptee, the giant and unruly Duke (Modern Family's Eric Stonestreet). But when they find themselves stranded on the New York City streets, they band together when they meet  Snowball (Kevin Hart), a rebellious bunny who demands that Max and Duke join his gang of abandoned pets on a mission against the humans who've done them wrong.

In anticipation for the home video release of The Secret Life of Pets (December 6) Fandango sat down with Stonestreet to talk about the movie. The actor also reminisces about his own dog, Coleman, who passed away earlier this year.

Fandango: Were you surprised by how well the film actually did in theaters?

Eric Stonestreet: I think everybody has expectations of what the movie would do. But I've built a career out of managing expectation. Then when it broke the records and all that kind of stuff, I was just pleasantly surprised. But I wasn't surprised that people responded to the idea, the notion of going to see a movie about your dogs and cats.

Fandango: When you first were approached for Secret Life of Pets, was it a no-brainer?

Stonestreet: Oh my God, I was over the moon. I didn't really even know that when I first went in and met [producer] Chris [Meledandri] that he was kind of offering me the project. He kept asking me, "What do you think, what do you think?" And I was like, "Well, it's going be a huge hit. Like, it's a great idea, I can't believe nobody's done it before." And he's like, "So what do you think?" And I'm like, "Yeah, like I said, it's awesome." And he's like, "No, do you want to do it or not?" And I'm like, "Oh my God, are you offering me, like... are you asking me? My answer is yes, of course I want to do it!" You've got to hit me over the head here, I guess.

Fandango: You're a big dog lover, right? How many dogs do you have?

Stonestreet: Well, I don't have any dogs anymore. My dog unfortunately died in April after 15 years. His name was Coleman. I wasn't able to talk about it too much right after Coleman passed away, but now it's fun to talk about him, because I get to remember all of the good times. Coleman's nickname was "The Patrolman.” Coleman the Patrolman, so his backstory was, all he really wanted to do was patrol the perimeter of my house. He was a very active patrolman. He was always on guard. He always put himself between me and wherever I was sitting. He was only 22 pounds, Jack Russell Terrier/beagle mix, so he wasn't a guard dog, and I always said, "If somehow I could let Coleman know that he wasn't 150 pounds," he would just not believe it, and I'm just glad he never knew he wasn't 150 pounds. He went out a proud 22-pound guard dog.

Fandango: Was he like the movie dogs, waiting by the door for you to get home?

Stonestreet: That was another thing that was so funny about him. He's a pretty independent guy. So me coming home... his attitude was like "Oh, finally had time to get home today, huh," you know. "So let me guess. Were you working? Were you out working? Well, things have been fine around here. The mailman came. I scared him off." I always wondered what Coleman's inner monologue and voice was, so it was an opportunity to definitely lend a little bit of what I imagined Coleman would think and sound like to the movie, for sure.

Fandango: What do you think Coleman would have thought about your performance as Duke?

Stonestreet: You know, I wondered that. I never could get him to watch Modern Family. I tried to get him to watch the show, to see if I could just at least see if he could recognize me on the TV, and he never really seemed to respond to it. I don't think he was a network-comedy-television guy. I think he preferred cable stuff. But I wondered if he would be able to hear my voice in The Secret Life of Pets, and watch it, so it was one of the bummers about him passing away when he did, is I never was able to get him to see if he could hear my voice coming out of the TV.

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Fandango: Any tricks you learned doing an animated voice for a feature film?

Stonestreet: I really liked kind of playing both parts in my head. I don't really know how other actors do it, if they just spout out the lines, or whatever. They always offer somebody to be in there to read with you if you want. Sometimes that's helpful, and then other times what I want to do is just hear the voice. I've said it before, being a little crazy kind of comes in handy, because I hear voices in my head and then I respond to them. I just like talking to myself, in a sense, in the booth. Where I'll say the line, in my head, but not out loud, and then respond to my own voice, to get that sort of back and forth exchange going.

"Being a little crazy kind of comes in handy."

You know, there are scenes in the movie between Kevin and Louis, and Louis and myself, that I would defy anybody to watch that and think that we're not standing there looking at each other talking. That's a testament to the editors and the director and everybody for really splicing that together and making it as though [Louis] and I are standing there having a conversation with each other.

Fandango: It's definitely one of the marvels of a great animated film, but it always prompts the same old question, “Did you and _____ work together in the booth?”

Stonestreet: I see the value in why they don't do that as well. You put myself and Kevin Hart and Louis C.K. in a room together... I would worry that we would end up costing everybody so much more money and so much more time because you just start improvising and making stuff up. So there really is an efficiency to have everybody sort of separated and doing it, and really just focusing on what you need and letting individuals improvise and trying to make that work, as opposed to putting three people in a room together.

Fandango: Did you help participate in some of the Blu-ray special features, like “Hairstylist to the Dogs”?

Stonestreet: Yeah, I did that! There's this famous groomer here in Los Angeles that grooms these dogs, and she does this great job. She has an Instagram page, I forget the name of it, but they had her walk in, and she kind of walked me through how to groom dogs. I wasn't very good at it, not surprisingly.

Fandango: Is there a possibility of a Pets 2, and what that might entail?

Stonestreet: I think there's a pretty good chance there will be a sequel, and I would have no idea what the story would be. That's sort of the great thing about animation, is I think they have a pretty solid idea of what the story is, but they're open to letting the story go where it might go based on performances, and that's really fun. So I think there'll definitely be a sequel, and as far as what it is, I'll be as surprised as you once I start recording it.

Watch The Secret Life of Pets, available now on FandangoNOW.