The teenagers who violently attacked rugby union great Toutai Kefu and his family members inside their home should be jailed for more than a decade because their crimes were "particularly heinous", prosecutors have argued in a Brisbane court.

Mr Kefu and his wife Rachel Kefu were stabbed and seriously wounded in the 3am attack inside their Coorparoo home, in Brisbane's inner south, in August 2021.

Their two adult children were also slashed during the home invasion.

The boys responsible, who were both aged 15 at the time, were due to face trial for multiple counts of attempted murder but pleaded guilty to the downgraded charges of malicious acts with intent earlier this year.

During a sentencing hearing on Tuesday, Daniel Caruana, who represents the teen who attacked Ms Kefu and her two children, said his client's offending did not meet the threshold to be sentenced to more than 10 years.

He described his client's actions that night as "reactive".

"I'm not trying to downplay what's happened. I accept the seriousness," he told the Supreme Court in Brisbane.

The teen had been diagnosed with Tourette's syndrome and had shown genuine remorse and insight into his actions, Mr Caruana said.

He had also worked on his education and mental health while in custody.

'Worst night of his life'

Mr Caruana told the court the teen had described the incident as the "worst night of his life" and what he did to the Kefus had "genuinely moved him".

"He isn't the same person now who committed the offences. He's matured and he's used that time [in detention] productively," he said.

The court heard at the time of the break-in, the two teens had never been charged before.

Despite their lack of criminal history, crown prosecutor David Finch argued the pair's offending should be categorised as particularly heinous.

This would legally allow for Justice Peter Davis to hand them a sentence of more than 10 years.

The second teen's lawyer, Laura Reece, said there was no "planned attack" against Mr Kefu.

Ms Reece told the court "as horrible as it was" her client wounded him in a "heightened environment", in which he was reacting to being charged at by Mr Kefu.

"The violence then is a reaction to that, rather than an intentional decision to pursue someone," she said.

Ms Reece told the court both boys had been drunk at the time and instead of fleeing the home they acted in "fear for themselves", "confusion" and "immaturity".

Ms Reece told the court the teen, who was born in a Tanzania refugee camp and was exposed to family violence, was living an itinerant life at the time of the offending and was "effectively out of control".

She told the court he had instructed her to read a statement apologising to the Kefus for the "serious and miserable" experience and the "unfixable scars" he had caused.

'If someone wakes up, just stab them'

Earlier in the night, the teens had decided to go out and steal cars and broke into another home, in Forest Lake, before targeting the Kefus.

Mr Finch told the court that the teens were drawn to the Kefus' two-storey residence, "simply [because of] the appearance and the nature of the cars parked outside" and they had discussed using weapons if needed.

"If someone wakes up, just stab them," he said one of the boys declared.

The court heard on Monday that at around 3am, Ms Kefu woke to noises downstairs. When she went to investigate, she discovered two teenagers who had broken in through a kitchen window.

When Ms Kefu asked, "what are you doing in my house?" the court heard one of the boys yelled, "f*****g shut up, we want the keys".

The court heard the teens, who were armed with a sickle and a knife, backed Ms Kefu down a hallway, and told her, "shut up or we'll kill you."

When Ms Kefu's screams woke her husband, the court heard he jumped over the stairwell banister to the lower level and pleaded with the teenagers to "do whatever you want to me but leave her".

The court heard during a struggle with the teens, Ms and Mr Kefu were both stabbed.

Ms Kefu's forearm was sliced so deeply that even with multiple surgeries, she has not been able to regain full function of it.

Her husband suffered a life-threatening stab wound to his abdomen and required emergency treatment.

Their 21-year-old son and 18-year-old daughter were also slashed as they came to their parents' aid.

Daughter's birthday 'real-life nightmare'

Ms Kefu relived the traumatic night through her victim impact statement, which she read from the witness box on Monday.

She told the court that August 16 used to be a happy day, as it was the day of her daughter's birth in 2003, and the same day her husband played his 60th test match.

"Fast forward 18 years … 16th August 2021 was a real-life nightmare," she said in evidence on Monday.

"I cannot erase these images."

Ms Kefu told the court at one point she believed both her husband and son had been killed.

Ms Kefu accepted the offenders were juveniles but "they are old enough to know the difference between right and wrong".

"To know there is no good excuse for their behaviour," she said.

"They must be held accountable for their actions, as actions have very real consequences."

The Kefus' neighbour, Ben Cannon, who was woken by the commotion, was also injured while attempting to apprehend one of the teens outside.

He told the court, "no words can adequately capture the shock waves of fear and devastation that rippled through our lives".

Mr Cannon told the court he could have "never anticipated the viciousness of the attacks".

"Their callous disregard for human life, coupled with the brutality of their actions, defy comprehension," he said.

Justice Davis has reserved his decision for a future date.