One-punch campaigner photographed with Brisbane bashing victim

Australian boxing champion Danny Green with Brisbane teen Cole Miller who died due to head trauma. Photo / Supplied

Cole Miller's grieving father sent Australian boxing champion Danny Green a photo on Tuesday that came close to breaking both their hearts.

It was a picture of Steven Miller's precious son and Green with their arms around each other, taken when the Brisbane teenager was in Perth at a water polo tournament two years ago.

Cole, 18, died on Monday in the Royal Brisbane and Women's Hospital's intensive care unit as a result of head trauma.

Two 21-year-old New Zealand men, Armstrong Renata and Daniel Jermaine Lee Maxwell, have been charged with unlawful striking causing death.

Green has waged a national campaign against the senseless violence of the "coward's punch", but when he posed for the photo with Cole Miller, he had no idea tragedy awaited his young friend.

"I remember Cole was a young kid so full of vitality," Green told The Courier-Mail yesterday.

"Cole's father sent me the photo yesterday and said, 'Look at this mate'. He was grieving badly but he said, 'I thought you'd like to see it'.

"He was incredible. He was thanking me for supporting the campaign against this type of violence when he'd just lost his son.

"It's impossible to know what to say to a father in that situation - I know how close they all were as a family.

"That's why this senseless violence has got to stop and it has to be drummed into people again and again just what can happen when you hit someone," he said.