It is alleged Joseph took the teen to the cinema on the day in question, something mentors were encouraged to do to build trust.
But afterwards, the court heard how they met up with the complainant's mother and spent the rest of the day drinking.
Joseph dropped off the other woman at home and continued with the "troubled teen" to Oakwood Manor motor lodge in Mangere where she booked a large studio room.
Earlier in the trial, the complainant told the jury how she persuaded him to join her in bed.
He told police he had repeatedly asked Joseph if she was sure she wanted to have sex and she had reassured him.
Though the incident only lasted 10 seconds, according to the boy, he had immediately felt uncomfortable and texted his mother,
"This day still haunts me ... f*** it still comes back," he said.
Mr McCaughan highlighted text messages sent by the defendant after the event.
"I forgot to say sorry for the other night ... actually I didn't want to apologise, I wanted to know how you felt about that," she sent.
"This is effectively an admission they had sex in the motel room that night," the prosecutor said.
The boy told her he loved her to which she later replied: "If I told you exactly how I felt I'd probably get sacked ... but every other part of me is 100 per cent real honest."
"I do feel a little the same as you."
While in the witness box, Joseph gave innocent explanations for the messages but Mr McCaughan labelled them a "sequence of self-serving lies".
"Her entire evidence was a deliberate strategy to try and answer the police case," he said.
The prosecutor told the jury she had lied to several people during the investigation and suggested they place no weight on her evidence.
The defence will close its case before the judge sums up and the jury retires to deliberate.
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