"I feel responsible for what happened...I was supposed to be taking care of him."
Manutahi was moved out of the intensive care unit because there was nothing else they could do, really, she said.
"I mean he can't talk or anything and he has had a tracheotomy now to help with his breathing. And he's being fed through a tube in his nose."
Talisha hoped the police would call with some news.
"The fact that there is still an investigation going on is good, but I wish they could find out who did it. It frightens me, it really does."
She said her dad Leo Kahui and little sister were living at Ronald McDonald House in Wellington, which was good for them.
"We can't leave Manutahi ... he knows we are here, he really does."
However, the stabbing into Manutahi's cheekbone had been so violent it had pushed a piece of bone up into his brain, and operating was too dangerous, medical staff told the family.
"It's really hard, because we don't know whether his brain will ever work properly again. It makes me feel so sad for my little brother. He is such kind person. He didn't deserve this."
"But the tracheotomy is helping his breathing and swallowing now. Of course, he can't talk or anything. Maybe he never will - I don't know."
Talisha said she was at her brother's bedside every day all day.
"I am here for him. He is very important to me ... he is very important to all of us."
Manutahi had come to Wanganui two months ago when his dad was forced to leave his rented house in Auckland.
Mr Kahui has said some of the family were gang members but not Manutahi. Mr Kahui is a Black Power member, and two of his other sons are members of the Tribesmen.
"He is a quiet and special boy who doesn't belong to any gang.
"He's a big 16-year-old but he's just a big kid, really - a big gentle, kind kid."
Detective Sergeant John Gleeson said inquiries continued, and police would like to hear from anyone who had information about the incident.