How will Jeremiah say goodbye to Gotham City? Cameron Monaghan’s character made a long-awaited transformation into what seemed like the famous villain during the February 21 episode. Whatever name you give him, he’s changed. However, we’ve seen numerous versions of The Jokers before and this is different — as is Jeremiah’s Gotham ending.

“I think that people are really going to react well to it; it’s something that I’m very proud of,” Monaghan, 25, says in the latest issue of Us Weekly, adding that the story has remained a secret to fans, which is important. “It’s funny, the thing with a prequel is that you kind of know where it’s all going in general, but sometimes you get these little, happy surprises and really amazing reveals that you don’t get to know [ahead of time] and this is one of them. This is one of those where I think it works.”

He adds: “I’m very psyched for people to see it. It was some of the most fun that I’ve had on the show. I also had a few moments of doing it when I was like, ‘Wow, I’m accomplishing a life goal while doing this. This is completely surreal.’”

Part of the reason the series has worked is because of the freedom the network and studio gave the actor, he reveals, noting that in the beginning there was “pushback.”

“It wasn’t until people became familiar with our version of the character and realized that this story, the universe was separate, that they instead actually started coming around the other way — they were asking for more,” she shares. “They wanted to see this character become realized. It was an interesting challenge obviously and a little bit nerve racking but thankfully the response has been overwhelmingly great. … This year is the most lenient they’ve been allowing us to dive in, and I think we’re really better off for it; I’m really happy with where the story goes. It feels like a very logical conclusion to it.”

And Monaghan’s to thank for a lot of that. The actor admits he sends back a ton of notes on each and every script.

“By season 3, I was pretty far off book and I was allowed a lot of room and leniency on the set to improv and to find stuff in the moment. And then as it got further into, especially this last season, [executive producer] John Stephens has been very kind and encompassing to me because I would send pages of emails of concerns,” he reveals. “It would be a scene that was four or five lines long, and I’d send pages of, like, ‘This is why I’m concerned about this.’ He was patient enough that we would work together and he would listen. I think that that’s why a lot of the performances come out really we ll, because the show allows the actors to play.”

While he can’t say much about his last day on set, the Shameless vet said he “felt good” when wrapping.

“The last scene that we shot was the last scene for the character, so I was able to completely experience, the journey and the last moment, I think it’s really wonderful,” he tells Us. “That being said, working with this character is exhausting – physically exhausting sometimes. We had worked a very long day. It was like a 19-hour day and I was sweaty and tired! I went home, ate pizza and slept for, like, three days.”

The role was also emotionally taxing on Monaghan, mostly because he cared so much about it.

“I’d get nervous about it, anxious. I have devoted thousands of hours obsessing about this over the course of five years. And that’s one of those things — sometimes it’s hard to just not be thinking about that,” he says. “I didn’t sleep before I worked on the show, ever, it’s just one of those things I just never slept. So when we finished up the show, it was kind of funny. I was like, ‘What do I do with my brain now?’”

Gotham airs on Fox Thursdays at 8 p.m. ET.