A 19-year-old man who took advantage of his aunt's hospitality by having sex with his underage cousin has been jailed for six months.
The man, who cannot be identified for legal reasons, confessed to having an incestuous "relationship" with the 15-year-old girl during an extended visit with her family in the Illawarra.
Court documents said the girl told police the assaults took place over a six-week period in July-August last year and included at least one incident where the teen said she was "pinned" to a plastic chair so her cousin could take advantage of her.
When arrested, the man admitted to police he'd been exchanging nude photos with his cousin for almost a year before travelling to the Illawarra to stay with her family.
He also admitted penetrating the teen and having her masturbate him, but told police his cousin had instigated some of the sexual touching.
He claimed during one incident his hand "fell onto her vagina" when she put his hand on her thigh, while on another occasion his fingers "slipped into her vagina" after she'd placed his hand down her pants and began moving her hips.
A series of text messages between the pair, obtained by police, shows while the acts were consensual, the girl repeatedly expressed her unease at their relationship and concerns her mother would catch them.
"We aren't doing it anymore, ever again," she wrote after one sexual encounter between them, prompting an "aww damn it" from her cousin in response.
He attempted to reassure her they would not be caught before telling her "but you are amazing, it feels so good".
She replied "I'm your cousin dude, I shouldn't be doing that shit".
The man left the house after an argument with his aunt - the girl's mother - over an unrelated matter, leading the teen to disclose the indecent acts to her mother.
During a sentencing hearing in Wollongong Local Court on Friday, defence lawyer Elizabeth Parkes said her client had expressed "remorse and regret" for his actions.
She said the man had had a deprived upbringing, suffered from depression and anxiety and and would be vulnerable in prison.
Prosecutor Jacqueline Azad told the court the man's behaviour had been "opportunistic but brazen" and that he'd breached the family's trust.
"To an extent he bit the hand that was feeding him," she said.
Magistrate Michael Stoddart agreed, setting a six-month non-parole period with an overall prison term of 15 months.
The man will be eligible for release on parole in February 2020.