In the upcoming episode of ABC’s “Once Upon a Time” Emma (Jennifer Morrison) must suffer the consequences of turning Hook (Colin O'Donoghue) bad.

A teaser for Episode 10 of Season 5, titled "Broken Heart," shows Hook taking out his new found evil nature on Emma. “I want to hurt you like you hurt me,” he tells a stunned Emma, who sheds a tear as she takes in the bad news.

In the episode, Hook will focus centuries of anger on Mr. Gold (Robert Carlyle), while Emma tries to get her love to move out of the dark mindset that he seems to have embraced.

Speaking to Popsugar, Morrison said that she was intrigued by the motivations behind her character’s slide toward darkness. “I think there's something really interesting about this idea that people make bad decisions for good reasons sometimes, and how far down you can end up in the rabbit hole for having made a bad decision but for a good reason,” she said, adding, “It's so easy to justify something when you don't know the domino effect of how far that can take you in life.”

The 36-year-actress says that she feels that evil comes from action and intention, and is not something that can just be born. According to Morrison, characters on the show who have turned dark have done so for good reasons.

The transformation into Dark Emma was a tough one for Morrison to make as an actress. “When you get angry or angsty in real life, it happens in a second,” she explains, “ But when you're angry as a character, for 16 hours a day, you have to sustain that level of anger and angst for 16 hours, so you wake up the next morning and go, ‘God, I didn't know I had those muscles! I didn't know I was carrying all this tension for so many hours!’”

The next episode of “Once Upon a Time” airs Sunday, Nov. 29 at 8/7c on ABC.