Iris Grace Halmshaw was diagnosed with severe autism in 2011, at just two years old. Her condition means difficult behavioural issues like obsessive behavior and erratic sleeping patterns.
After hearing of the potential benefits of how much interaction with animals can help autistic children, her parents decided to give it a try.
They first tried it with dogs and horses, but nothing worked until they saw how Grace responded to her uncle's cat when they were taking care of it for a few days. Iris' parents then decided to get a cat in 2014, which is when Thula came into their lives.
Iris' mum uses a Facebook page to document the sweet friendship
Since then Iris and Thula have become inseparable. They take baths together, play together, and sleep together.
'Thula loved all of the things that Iris found difficult' her mum Arabella Carter-Johnson told CNN. 'It was like heaven.'
Writing about her daughter's condition, Iris' mum said on her website: 'Eye contact was a rare occurrence, she didn't want to or know how to play with us, showed obsessive behavior, got desperately distressed when we took her near any other children and her sleep patterns were all over the place.'
Iris started making substantial progress after they got Thula. She hated the sensation of having things like water touching her skin but because Thula is a water-loving cat, she kept her company in the bath.
The cat seemed to adapt to Iris' behaviour according to what she needed, distracting her during stressful times until she settled again.
Iris also began to speak after Thula's arrival, giving her instructions like 'more cat' or 'sit cat'.
'It's beautiful watching this', Iris's mum told CNN. 'We're her parents and educators. It's calming to know that she has her little buddy, and someone other than just us.'
Aside from the very special relationship she has with her cat, Iris is also famous for her painting. Arabella introduced it to their homeschooling curriculum, and the activity became something that helped mother and daughter bond.
'She looked at me and wouldn't push me away. It was a way for us to connect.'
The talented little painter even counts celebrities like Angelina Jolie among her clients, and has been called the six-year-old Monet.
Her artistic pastime is also one of the things helping Iris, and her mum is looking forward to her daughter becoming more and more independent.
'I'm hopeful for more improvements', Arabella said. 'One day, I want her to be able to get a job and live independently, and we will try our absolute best to make that happen. Autism doesn't have to be this grim diagnosis - it's seeing the brilliance in differences and embracing those.'