The teenager stabbed in the face in Wanganui will spend Christmas in intensive care at Wellington Hospital.
Manutahi Edwards was stabbed in the face with a screwdriver last week, reportedly because he was wearing a blue cap, a colour associated with the Black Power gang.
The attack happened about 7pm on Wednesday on the corner of the Keith and Glasgow streets.
He was initially taken to Wanganui Hospital but transferred overnight to Wellington Hospital's Intensive Care Unit.
His father Len Kahui said medical staff had told him that the back of his son's brain was swelling.
"It is the part that controls his breathing, swallowing and controls the temperature of the blood. So they said there was no way Manutahi would be leaving the unit for weeks. They said he will be there till after Christmas."
Medical staff told Mr Kahui on Sunday that the stabbing into Manutahi's cheekbone had been so violent it had pushed a piece of bone up into his brain.
"The bone is in a bad position and the doctors said it was too dangerous to operate (and) that only time would be the healer."