Natalie will fall in love with the River Boy in episodes to air this week on Australia's Seven Network and in September on Channel 5 in the UK.
Catherine Mack, who plays Natalie, told TVWeek: "She can see through his act. She believes with her whole heart he's a good person. She will not stop until she makes him realise that.
"It kind of just happens. She wants to help him and soothe him. Then, it's on, and neither of them is thinking about what they're doing. Caution is thrown to the wind.
"There's chemistry and electricity between them. But, the minute it happens, she's thinking, 'Oh my God, have I crossed the line?'"
Steve Peacocke, Summer Bay's Brax, added: "When he's at a low point, she pounces. He's vulnerable and he thinks, 'Why not?'"
However, Peacocke added that the pair begin to "regret" and "rethink" their actions in the following days.