A teenager who was attacked on a Perth train 10 months ago has died.

Laoa Faafua never left hospital after he was punched in the head by a stranger in January this year.

Mose Faafua said his brother had shown signs of improvement and was even speaking again before he died yesterday after suffering a massive bleed on the brain.

“I think he just had enough,” Mr Faafua said.

“He's having a rest now. He's in a good place.”

Camera Icon Laoa Faafua (rear) pictured on the with the man who pleaded guilty to assaulting him. Credit: Seven News.

A 19-year-old has pleaded guilty to the assault. He was due to be sentenced for causing grievous bodily harm in two weeks.

Mr Faafua told Seven News the heartbroken family now want his attacker's charge upgraded.

“He can just walk around and eat and drink and do what he wants to do while my brother was suffering,” Mr Faafua said.

Camera Icon Mose Faafua says his brother will be missed, but never forgotten.

“We're going to miss him, but we'll never forget him.”

Laoa's loved ones want to thank his rugby club for paying his medical bills.