At his sentencing last week the court heard that Samoa got his hooks into the girl at "a very difficult time in her life when she was particularly vulnerable".
After he groomed her and exposed her to images and suggestions no 13-year-old girl should know about, she began to travel down an even darker path.
"Around the time she met you, she went down a spiral," Judge Claire Ryan told Samoa, referring to a victim impact statement the girl's mother wrote for the court.
"She had behavioural problems, she stopped going to school - she began using drugs including intravenous drugs and alcohol."
"This time of her life had a significant impact on her," Judge Ryan said.
"Her mother believes she will feel the effects for the rest of her life. She engaged in such risky behaviour - much of which could have led to her death.
"She was suicidal, went on methamphetamine binges and self-harmed, cutting her arms and wrists.
Her self esteem plummeted - missing so much school and feeling so behind only made that worse - and she "carries mental and physical scars daily".
"When Victim A met you, she was really vulnerable and you took advantage of that," her mother told the court.
"Children should be safe, adults should help them - not take advantage of them."
When he didn't get his way with Victim A, Samoa turned to other young people to get the sex he was craving.
Over 15 months he groomed and persisted with three young people in total - but the courts heard that his offending was not constant over that time period.
Samoa had always considered himself straight, but when he met Victim B and Victim C - both teenaged boys - he was more than willing to try his luck sexually with them.
Victim B was 13 when he chanced upon Samoa online.
Samoa said he was 19, and that his name was Alex.
They exchanged messages through social media applications Viber and Whisper, sent texts and spoke on the phone.
He'd been bullied and was desperate for a mate, someone he could talk to, who understood him.
He never imagined he would fall into the clutches of a sex offender.
Samoa's messages became increasingly explicit - he'd describe sexual acts he wanted to perform on Victim B, and told the boy what he wanted done to him.
He sent a video to the teenager of himself masturbating, asking "you want this in your mouth?".
Until then, Victim B had been considering meeting "Alex", but the obscene video made him uncomfortable and he went to his mother and told her everything.
She read a statement in court last week, speaking clearly and firmly at Samoa, who stood in the dock staring at the floor for much of his sentencing.
She said her son felt "extremely guilty" about his contact with Samoa, especially for disclosing the address of his family home.
Even when he started to feel uncomfortable, her son continued to message the predator because he lived in fear that Samoa would come after him, murder him, hurt his family if he cut off contact.
His mother said the teenager was "immature for his age".
"You exposed him to things he should never have seen or heard," she said.
"No child should have to deal with this type of situation."
She said her son's trust in people was severely damaged and he was going through a slow and painful process to rebuild his life.
Her family were also struggling, having been "dragged into a scene they knew nothing about".
There had been many sleepless nights caused by worry and the thought of Samoa manipulating her son to sneak out of his bedroom window at night to meet and be abused was "frightening".
Nabbed: How police caught deviant Andy Samoa
Detective Inspector John Sutton said police took the complaints from the boys separately, but soon clicked that the offender was the same in both cases.
They had no idea who he was, so embarked on a covert operation to catch the predator.
He became lonely and had a high sex drive so wanted to meet people to help him with that.
He said he never intended to offend, but the court reminded him repeatedly that he knew exactly how old each of his victims were when he abused or groomed them.
Samoa admitted during his interview that he "considered the possible consequence" but went ahead anyway.
Judge Ryan said Samoa feigned remorse, but that was more likely because he'd been caught.
"Your remorse, in my view, is extremely limited - largely for the predicament you are in," she said.
"You seem to lack insight into the severity of your offending, trying to excuse it."
She said Samoa had put forward an address to the court, hoping for home detention - but the occupants refused to have him there because they had children visiting regularly.
Prison was the only option.
And she considered Samoa - because of his attitude towards his offending - was too high a risk for any other form of punitive action.
"You claim you are a good person [but] your offending was premeditated and involved the grooming of young victims.
"You were surprised at yourself for engaging in sex with young males, you believed yourself to be heterosexual - you were aware of your victims' ages but you said you were lonely and had a high sex drive, that's why you groomed them."
Judge Ryan said Samoa's actions indicated he had "developed a deviant sexual interest" in young people.
He must serve 50 per cent of his sentence before he can seek parole.
Help your kids stay safe online
Some things you can do to help your children stay safe online include:
• install software on your computer that either blocks restricted content so your children cannot access certain sites, or monitors activity so that you can review online behaviour
• know who your children are contacting online. If they are not your children's actual friends then question their cyber friendship
• know which social networking sites your child is on and what information they are posting
• check that your children understand the dangers of posting personal information on social networking sites