Rapist Nicholas Ninow's grandmother Pauline Gericke said on Tuesday that he was a good boy who played sport and was loved by many when he was at school.

"He played cricket, gymnastics and was liked by everyone," she said. "He becomes delusional and aggressive [on drugs]. He sometimes becomes a maniac. He looks different, he speaks differently."

Ninow has been convicted of raping a seven-year-old girl in the toilet of a Dros restaurant earlier this year.

The court heard earlier on Wednesday that Ninow moved in with his grandmother during his "chaotic" upbringing. Gericke said things were going well, and that Ninow might never have raped the child in the Silverglen, Pretoria, restaurant had his mother not moved in with them.

Ninow's mother asked to move in with Gericke because she was living on the streets with her other son.

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She told the court that Ninow took drugs for the first when he visited his mother. She said Ninow became hooked on drugs, and had never stopped.

"He tried, but he failed to get clean," said Gericke.

Ninow sobbed uncontrollably as his grandmother gave evidence.

"The fact that he had been drinking for three days and bingeing on drugs might have had an effect on his behaviour. He would never harm a child. Never," said Gericke, breaking down in tears.

She said there was a good side to her grandson, whom she had raised since he was eight years old.

"There is a side to Nicholas that I love, there's a side that I raised. I am not saying he should not be punished, but I believe there is another side to Nicholas. There are mitigating factors," she said.

Asked what he would like to say to the rape victim and her family, Gericke said: "I would like the opportunity to talk to those parents to tell them how sorry I am. I know Ninow is so sorry. I know he is heartbroken for that child," she said.

The trial continues on Thursday.