BEVERLY HILLS, Calif. — William Fichtner considers his lengthy stay in the Fox series “Prison Break” to be a break from the normal stresses of being an actor.

“This ended up being a lot longer than I thought,” said Fichtner, the Cheektowaga native who plays Alexander Mahone in the series and also has a small role in the blockbuster movie “The Dark Knight.” Fichtner’s “Prison Break” character is an FBI agent who started chasing brothers Michael Scofield (Wentworth Miller) and Lincoln Burrows (Dominic Purcells) in Season Two but ended up in prison with them in Panama during the third season.

“My wife asked, ‘Are you having a good time?’” Fichtner said in a recent interview with a few television critics. “I said, ‘Doing a series is like taking a break from the business. It is the closest thing you’re going to have to a real job.’”

He originally signed on to appear for two seasons but was talked into doing a third and final one by writer-producer Matt Olmstead. The show’s move from Dallas to Los Angeles to film was an inducement for Fichtner, who in the past had to leave his family in Glendale, Calif., to shoot.

“The bottom line is, if I didn’t really have a good time doing it, I wouldn’t have come back for one more year,” Fichtner said.

As he talked, he showed some surprising interest as Fox prepared to start a session on the reality series “So You Think You Can Dance.”

“My wife got me hooked watching this show,” he said. “It’s unbelievable.”

He also revealed a love of gardening. “I’m always working on my yard. ... I have a big backyard with plants and trees. I look out the window in the morning and ask, ‘Why is our rose bush tilting?’ I’m obsessive.”

Who knew the guy who has played so many villains had such a soft side.

“All I am is a soft side,” Fichtner said. “You can’t play people like Mahone living with a hard edge in your life. ... People think, ‘Mahone, a hard guy.’ You’re missing what I’m trying to do.”

He’s been pleased by the challenges he’s been given to play Mahone.

“The only thing I ever asked the writers was to make it a really difficult journey,” Fichtner said. “Challenge me. ... The things they’ve thrown Mahone’s way probably have been a little on the difficult end.”

When Olmstead asked him three months ago to return, Fichtner only had one request.

“I reminded him to make it challenging,” Fichtner said. “If I’m just going to walk in and ‘get the bad guy,’ I’ll be asleep by the end of that sentence.”

At the end of Season Three, Mahone and the brothers escaped from a Panamanian prison. In Season Four, which returns with a two-hour special on Sept. 1, he and the brothers are allies in a mission to seek justice.

“There is an event that happens in the first episode that will be my through line throughout the season,” Fichtner said. “It reshapes everything.”

Working with Ledger

Fichtner, who returns frequently to Western New York to visit family and was here on July 4, did have time during a break from “Prison Break” to film a scene in “The Dark Knight” with the late Heath Ledger. He was asked by director Christopher Nolan more than a year and a half ago to play a bank manager in the scene in which the audience meets the Joker.

“I said, ‘Send me the pages,’ ” recalled Fichtner. “I read it and thought it was really cool. ... When they break in my bank, I have a reaction to it that is not your typical bank manager.”

The scene enabled Fichtner to get a glimpse of what Ledger was going to do with his last big role before his death. “What a sweet guy,” Fichtner said. “I’m a fan of his. It was kind of cool to get a glimpse of what he was thinking. ... I was impressed.”

Leaps of faith

“Prison Break” started its run critically acclaimed, but it has become increasingly preposterous by sending its characters back to a different prison after they escaped the first time. A great original idea has become increasingly silly to keep it alive.

“It is a show of pace,” Fichtner said in defense of the show. “There are moments that, if you stop and take every sentence or thought and break it down, you might confuse yourself a little bit. You have to take a leap of faith here and there.”

The actor has had his own concerns at times, telling the writers that some things they’ve asked Mahone to do didn’t make sense for his character.

“After six or seven episodes, you want to know about Mahone, ask me,” said Fichtner. “In one episode last season, I thought everything the guy did was not really Mahone. I sat down with the writer and we tweaked the whole thing.”

And just who is Mahone in Fichtner’s eyes?

“It is very clear what Mahone’s journey is,” Fichtner said, referencing the character’s drug and marriage problems. “All of a sudden the blinders went up, and he couldn’t see the forest from the trees. And little by little, he’s trying to make his way back.”

Fichtner has a couple of thoughts on how Mahone’s journey should end.

“Have it be something really out of the blue,” said Fichtner. “What if he totally loses it?”

Sounds challenging.