His mum, Theresa Meachen, said Black Thunder was a great companion for Taine throughout his treatment.
"For Taine he brought so much joy. It just gave him that little bit of hope and it gave him a distraction. He is like his best buddy. Taine will get upset if he thinks that there is something not right with Black Thunder.
"He really loves him."
Meachen said Black Thunder, who has grown from the size of Taine's hand to about 30cm long since they got him in 2016, doesn't go far from her son's side.
"I think he is more scared of losing Taine than Taine is of losing him. Taine will watch TV and Black Thunder will just sit on his lap.
"He goes to the beach with us on holidays. He's part of the family."
Taine finished treatment in February, which he celebrated with a trip to the beach and some fishing with friends and family.
He will have another opportunity to celebrate on Thursday at Auckland's Royal Easter Show.
More than 220 people, including sick children who have made wishes through Make-a-Wish and their families, will be there for a reunion hosted by the charity and Cadbury.
"He's excited. What kid doesn't like to go to a show with fun and excitement and rides and chocolate," said Meachen.
More than 120,000 are expected at Auckland's ASB Showgrounds over five days for this year's event.
The jam-packed line up includes lumberjacks, bulls the size of small cars, sheep shearing and entertainment from Zirka Circus and Kiwi band Sons of Zion. There will also be carnival rides and fireworks.
This year marks 175 years of the A&P show, which brings country life to city slickers.
The show runs from March 29-April 2. Entry is free and tickets for activities can be bought on site.
