While speaking to The Hollywood Reporter, Wells and series star William H. Macy explained that it was the exit of Noel Fisher — who played Mickey Milkovich — that anger hardcore fans of the show the most.
"John got death threats when Noel left. People loved Mickey and Ian [Cameron Monaghan] together," Macy shared.
"I was tempted to give everybody Noel's home phone number so they could call him and say, 'Why aren't you coming back?!' instead of threatening me all the time," Wells added.
The two went on to talk about how the show and how long it could potentially run considering series co-star Emmy Rossum is now leaving and the original BBC series that Shameless is based ended after 11 seaons.
"There's no end of stories about maturing in your own family and the pull that families have on us," Wells stated. "Placing that within the structure of people who are struggling economically and who have to depend upon each other to survive provides endless story material. It's always a question of how long a cast is prepared to keep playing the characters."
"I could write this for another 10 years," he added. "The satirical underpinnings of this notion that there really is class in America is something that we could write about forever. Every day you pick up the paper and there are 10 other stories you could tell."
"I know there's another 10 years of stories, and I'd love to see them," Macy added. "But when I think about acting them my back starts to hurt a little bit. (Laughs.) I know I want to do another season or two, and after that we shall see."
Macy then went on to share how he would to see his time on the show wrap up. "John once said that he doesn't see a big splashy ending; the camera just goes from shining a light on the Gallagher house and it moves a couple of streets over and the Gallaghers just keep on going," he said, later quipping, "Other than that, I'd rather Frank's ending not be testicular cancer!"
"Or a terrible brain tumor," Wells jokingly interjected. "When Anthony Edwards was making the same decision that Emmy did, to leave ER, we gave him [character Mark Greene] a brain tumor. And when I told him what the story was, he started the conversation by saying, 'As long as I don't have a brain tumor.' "
Shameless airs Sunday nights at 8 p.m. ET on Showtime.