The man responsible for the stabbing, 27-year-old Aidan Conaughton, was sentenced to imprisonment at the County Court of Victoria on Friday.

Judge Carolene Gwynn said Conaughton delivered multiple blows to the 18-year-old victim's stomach and buttocks and he would have foreseen the high probability of serious injury when he grabbed the knife.

"The attack occurred in a family home... this is an environment where they were entitled to feel safe," she said.

The court heard the victim had contacted an associate to ask for a lift to his grandmother's Ballarat house where he lived earlier on the night of August 1, 2020.

Conaughton was with the associate and drove to pick up the victim, taking him back to a Sebastopol property.

He and two other men attacked the victim at the property, while the victim tried to defend himself by curling up on the couch.

The victim suffered a fractured eye socket and was bleeding from the ears.

"It does not appear you had any history with him and had no reason to be involved in the initial assault upon him," Judge Gwynn said.

"The attack in Sebastopol was three on one, placing him at disadvantage and making him vulnerable... he would have been caught by surprise and had limited ability to defend himself in the sustained assault.

"It was cowardly."

Judge Gwynn said 'of course that should have been the end of the matter' but Conaughton then went on to tell the victim he could go home if he gave them $50,000.

The victim gave up his property 'but it wasn't enough'. Conaughton drove the victim to his grandmother's house with intention to steal his property.

He used the victim's keys to get into the front door and went into the victim's bedroom where his partner who was in bed woke up to find the victim bleeding and with cuts to his face.

"As a group you took him bloodied and beaten to his own home distressing his (partner) and (grandmother)," Judge Gwynn said.

"You entered a private home in company and in the early hours of the morning in extremely intimidating circumstances given the assault that had just taken place and the demand for the (victim's) money."

The court heard Conaughton began going through the victim's drawers asking 'where is the money' before grabbing a knife during a struggle with the victim.

Conaughton swung the knife at the victim and then stabbed him in the stomach three times and in the buttocks once before fleeing from the home with the co-accused.

The victim's grandmother woke to 'blood-curdling' screams and her grandson's plea for help before he collapsed on the ground.

The victim spent a week in hospital and he required an external colostomy bag for more than six months due to his perforated bowel.

Judge Gwynn said she took into account the grandmother's victim impact statement that was read during the plea hearing, detailing how she no longer felt safe in her own home and experienced anxiety and hypervigilance.

She said she also considered Conaughton's plea of guilty, expression of remorse, criminal history of 13 court appearances including assault and causing injury charges and difficult circumstances in his upbringing.

"It would appear relatively short periods of imprisonment have not deterred you nor have (treatment) orders assisted you to date," she said.

The court heard Conaughton had used drugs since his teenage years and experienced periods of homelessness, was diagnosed with ADHD, depression, PTSD, oppositional defiance order and autism.

A psychologist made an assessment that without significant therapeutic intervention, insight and a willingness to engage in services, Conaughton's prospects of rehabilitation were limited.

Conaughton was sentenced to three years and 10 months imprisonment with a two year and eight month non-parole period.

He has already served 557 days in pre-sentence detention.

The court heard Conaughton plans to relocate to Gippsland after his release from prison.

If you or someone you know is impacted by crime, call the Victims of Crime Helpline on 1800 819 817 or visit www.victimsofcrime.vic.gov.au.

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