A dramatic plot for the pair - played by Claire Cooper and Anthony Quinlan - begins later this month when they share a drunken kiss amid problems in their respective relationships with Rhys Ashworth and Lynsey Nolan.
Things soon go a step further, but events later take a startling turn when Jacqui claims that Gilly raped her on the night in question. Gilly, meanwhile, confirms that he had sex with Jacqui but insists it was consensual.
Speaking to Soaplife about the gritty plot, Claire Cooper explained: "They're telling the same story but are looking at it from different angles. Just who to believe is a very grey area. It will split the village and the viewers."
Discussing whether Gilly did rape Jacqui, she continued: "It's what Jacqui believes happened. She agrees she was drunk and kissed Gilly but she didn't want sex and she's convinced she was raped. She thinks she made it clear to Gilly she didn't want sex but somehow he didn't get the message."
As the plotline continues, Gilly is arrested and charged after Jacqui reports him to the police. However, as Gilly continues to protest his innocence, many of the Hollyoaks residents - including Rhys - will be unsure of who to believe.
Asked whether she knows the outcome of the storyline, Cooper replied: "No. Neither of us do. We don't know what happened that night. We've just been told that our characters each think they're telling the truth. [Anthony] and I have talked about it a lot. I even read his scripts to try to work it out. The outcome will be a surprise for both of us."
The storyline begins on Monday, February 14 at 6.30pm on Channel 4.