Actress Moon Geun-young has come a long way from the wide-eyed teen who won audiences over in saccharine rom-coms like “My Little Bride” (2004) and “Dancing Princess” (2005).

Shedding her sugar-sweet persona, she took on one challenging role after another, beginning with SBS’ “The Painter of Wind” (2008), where she evocatively straddled the gender line as renowned Joseon period artist Shin Yun-bok.

Undeterred by low viewer ratings, Moon continued to push the envelope with the soap-operatic “A Sister of Cinderella” (2010), where she tried on pessimistic for size.

Sullen yet honest proved a winning combination. The KBS series drew in average ratings of 17.9 percent, earning it a seat on the Wednesday-Thursday night prime time throne.

Not one to try to reap the windfall of a small screen success, the 23-year-old maverick gave the stage a spin, picking Patrick Marber’s powerful play, “Closer,” as her thespian rite of passage.

She caused a stir as the strip dancing, promiscuous Alice (played by Natalie Portman in the movie adaptation), driving the message home: Moon was all grown-up. 

Which is why when news broke that she was cast in the KBS rom-com “Marry Me, Mary!” more than a few might have raised their eyebrows.

Why after tackling all those risky, plucky roles would she return to a syrupy, youthful romance?

“I was simply charmed by Mary’s character,” said Moon at the drama’s press conference on Wednesday.

The actress ― decked out in a strapless affair ― explained how she selects characters that help expand her repertoire, not, as some might assume, to break a mold or stereotype.

While at first glance Moon might appear to be taking a step backward, in truth, her new role represents an interesting step forward.

The last time she starred as an unwilling bride subjected to an arranged marriage, she played innocent and guileless, a helpless victim to her situation.

This time around, she takes matters into her own hands.

Her new character is an optimistic, perky yet directionless 20-something who, when confronted with the threat of an arranged marriage, convinces indie band singer Mu-gyul (“He’s Beautiful!” star Jang Keun-suk) to pretend to be her husband.

Things don’t work out the way she intended, and Mary finds herself entertaining potential romances with two men, her intended husband, the wealthy Jung-in (“Coffee Prince” actor Kim Jae-wook), and lead vocalist Mu-gyul.

Charmed by Jung-in but in love with Mu-gyul, Mary must decide whether or not she wants a pragmatic or a romantic future.

Jang, cast yet again in the role of a band member, sung nothing but praises for his precocious co-star, describing her as “very honest and lacking in pretension.”

“I was attending a meeting at the production company when I heard Moon was cast and cried out, ‘Hurrah!’ right then and there,” he said.

“I wanted to work with someone around my age,” Jang, also a former child actor, elaborated. “And I thought that Moon would have experiences of growing up that were similar to mine.”

Indeed, both Moon and Jang have managed to make the transition from child star to adulthood, all under the intense scrutiny of the public eye.

At the press conference Wednesday, Moon drew from her well of personal experience and reached out to teen star Ko Ah-seong.

“The Masters of the Art of Study” actress Ko has been under fire for her early admission into Sungkyunkwan University, after news of her entry through rolling admissions spurred rumors that she is receiving preferential treatment.

“I did not do anything shameful, but because I am a celebrity I was criticized and treated like I did something wrong and it was really hard so much so that I felt like I lost my sense of pride,” said Moon, who suffered through a similar experience when she was admitted into Sungkyunkwan University several years ago through the same route. “But if she is able to stay strong and confident, then I believe she will be able to get through this.”

As she expressed emotional support for actress Ko, Moon seemed wise beyond her years. Every now and then, however, Moon revealed flashes of youthful innocence.

When the topic of marriage came up, she talked about how she used to dream of getting married when she turned 24 or 25.

“Because that is when my beauty will peak,” the young actress explained in a moment of girlish naivete, pressing her small palms up against her rosy cheeks and smiling.

“Marry Me, Mary!” ― an adaptation of “Full House” comic book artist Won Soo-yeon’s recent series ― starts airing Nov. 8 on Monday and Tuesday nights at 9:55 p.m. on KBS 2 TV.

By Jean Oh (oh_jean@heraldcorp.com)