The story of Dr. Jekyll and his evil alter-ego, Mr. Hyde, is legendary: Desperate to save his comatose father by curing the evil that lurks in the human soul and causes illness, the good doctor makes a mess of things and succumbs to madness himself.

Constantine Maroulis' life story may lack the dire drama of Jekyll's, but his family history has shaped Maroulis' approach to playing the dichotomous doctor.

Maroulis, a former American Idol contestant, stars in the revival of the musical tragedy Jekyll & Hyde, a late-'90s Broadway smash by songwriter Frank Wildhorn and lyricist/author Leslie Bricusse that hits the Forrest Theatre for a five-day run starting Wednesday.

Big brother Athan, an industrial-goth electronic-rock notable during his time with the Philly-based Executive Slacks (1987-1990) and Tubalcain (1991-1993), influenced Maroulis' gothic interpretation of Jekyll/Hyde.

And Maroulis' own relationship with his father, James, also contributed to his understanding of the character. "He's a sick man now, my father, so I know about Henry's plight," Maroulis explains.

The rocking Maroulis, 37, is now better known for snagging a Tony Award nomination with his performance originating the character Drew in the satirical '80s hair-metal musical Rock of Ages - Off-Broadway in 2008, then on the Great White Way in 2009, and with the national touring company in 2010 - than he is for missing out on Idol in 2005.

Since Rock of Ages, the howler, 37, has won the title role in Bon Jovi keyboardist David Bryan's follow-up to his Tony-winning Memphis musical, The Toxic Avenger.

"Theater has always been where I wanted to be since I was 7 years old," says Maroulis by cellphone while walking down a street in Dallas, fresh from making several purchases at a vintage-clothing store. "I owe that mainly to my brother, Athan."

Though the Greek American family started out in Brooklyn, the Maroulis clan moved to Wyckoff, N.J., when Constantine was 7. And by the time he was in his teens, the young Maroulis had been in Philly many times to see Athan play at now-defunct clubs such as Revival. "That's why I'm most looking forward to our Philadelphia run - my brother's roots there," says Constantine, with a bit of family pride. "Visiting him there was always a big deal. He lived so large. It was a lifetime away from how I was living as a kid."

Athan turned Constantine on to nearly all the rock records that he would devour. But there were Broadway classics, too, in the Maroulis family collection. "I fell in love with stuff like the booming '70s-film-version soundtrack to Jesus Christ Superstar," he says with a laugh. "And the movie of West Side Story. Every time it came on television, my mom pointed out that there were Greeks in the cast."

Particularly influential was Athan's performance as Bernardo in a high school version of the Bernstein/Sondheim musical. From the older brother's costume of skinny ties and tight black jeans to his death scene, Constantine was moved by the theatrical experience. "I wanted to be just like my brother. West Side Story's rumble scene where Athan got killed, I got scared because it was so real to me. That was daunting." Thrilling, too. Constantine wanted to be part of it.

Other influences had their effect, too. Being wowed by Bon Jovi as a kid certainly was a talking point when Bryan brought Maroulis in last year as the giant green man for The Toxic Avenger musical. "Do you know how weird it was, having come off of doing 'Wanted Dead or Alive' in Rock of Ages to working with the guy daily?" says a laughing Maroulis, who also cites the Doors and Jane's Addiction as inspirations.

Yet, in talking about Jekyll & Hyde, he turns attention back to his family. The way Maroulis views the Jekyll/Hyde character stems from goth-music legends that his brother turned him on to, such as Bauhaus, renowned for its gloomy imagery and the bleakly anthemic "Bela Lugosi's Dead."

"That goth iconography was part if it, yes, but I brought my own heart to Henry, and that starts with his humanity," Maroulis says. "There's a young, talented, successful doctor with a beautiful fiancee with seemingly everything right in his life, yet that complex relationship with his father drives him to want to help him. There are doors slammed in his face. I can relate to a lot of that."

There haven't been many doors slammed in Maroulis' face since he was booted off American Idol in 2005. The singer and actor - who trained first at the Boston Conservatory, where he received a bachelor of fine arts degree in musical theater and then apprenticed as an actor at the prestigious Williamstown Theatre Festival in the Berkshires of Massachusetts - has been on an upswing since he joined the cast of the Broadway musical The Wedding Singer in 2006. "That's where I got to show off my comedic chops," he says. After that, in 2007, a shot in the intimate Off-Broadway musical review Jacques Brel Is Alive and Well and Living in Paris showed off his dramatically subtle way with highly personalized song. "That show," he says, "was intense."

Since that time, Maroulis has strived to keep up that intensity, first by working with top-notch pros such as Jekyll & Hyde's Wildhorn, then by imbuing each part - as in his most recent pair of roles - with passion, guile, and vigor. Jekyll & Hyde had more than 1,500 Broadway performances from 1997 through 2001, but Maroulis says he made the role his own, "rather than any past versions."

What's different this time?

"This version is a sexy, gothic, Victorian romance with a modern edge that we rocked out," Maroulis says. "And when I get this moment in Act I, my transformation scene when I sing 'This is My Moment,' all I can say is . . . that's when I know I'm truly where I belong."