Dylan Catterick went "downhill" quickly after his four-month-old brother, Josh, was diagnosed with a mandarin-sized tumour in his brain.
Part of it was the shock diagnosis. Josh wasn't eating and mum Kylie had planned to take him to the doctor in the morning – but after another missed bottle she acted on instinct.
"If she had waited until morning he wouldn't be here," Dylan said.
"Just the fact we were that close and the only reason he's alive is because she had a gut feeling still scares me today. It will keep me up at night."
Two years ago doctors operated on Josh to remove the tumour and his condition is now stable, although he has ongoing issues with cerebral palsy, hydrocephalus and delayed learning.
But Dylan, now 16, needed ongoing help too.
After Josh's diagnosis he stopped attending school regularly. Locking himself in his room, he would not talk to anyone, but worried himself sick about his brother and family.
In November Dylan and his mum, Kylie, who live in Bonner, went to an Australian-first conference in Sydney for the families of people diagnosed with cancer, organised by CanTeen.
"We often think of the patient when it comes to cancer," CanTeen chief executive Peter Orchard said. "The reality when it comes to cancer is that it's such a big thing, everyone gets turned upside down by it."
The organisation's research shows that young people with cancer in their family have five to six times higher levels of distress than the rest of the population.
In some cases, distress can develop into "really dark" thoughts about self-harm.
Talking to others at the conference was about more than finding people who would understand what Dylan was going through, although that was a huge part of it.
"I'm no longer alone", is one of the most common things CanTeen hears from parents and siblings after they meet others who are going through a cancer diagnosis.
"When you have a child diagnosed with something like this you become part of a world," Mrs Catterick said.
"It's just comforting and reassuring to hear other parents dealing with similar issues, having the same thoughts, it makes [you feel] ... you're not alone, [that] your reactions are normal so you're not going mad."
Dylan said he's learnt to make time for himself and his own life outside of Josh, doing the things he loves like reading, gaming on his PlayStation or just seeing mates.
He also finds time for CanTeen camps. "It's so good finding people you can talk to about it."