On her YouTube page Nikki Lilly, she shares makeup tips, cooking videos and more, racking up over 2 million views.
Christou is also an inspiration for others. She suffers from an arteriovenous malformation, or AVM, abnormal tangles of blood vessels that disrupt the connection between the arteries and veins.
Though she was born with the condition, the effects did not appear until Christou was 6 years old. Large veins started showing up on the right side of her face, accompanied by swelling and bleeding from her nose and gums.
"It was really scary and I did feel sorry for myself at first, but then I realized there are so many things I can do," she says in a video. "So when I was eight, I started my YouTube channel, and created tons of best friends."
"I just saw it as a hobby that I really enjoyed doing when I was at home because of my illness," Christou tells PEOPLE. "So when other children were playing outside I was editing and filming my videos."
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"I have always been interested in make-up and beauty," she tells PEOPLE. "I remember watching my mummy and my cousins putting on makeup and being mesmerized. I thought it was magical how you could be transformed."
"And [my YouTube page has] been a massive confidence builder because I was really unconfident," she says in the video. "I used to look at myself in the mirror and think, 'Where have I gone?' I used to wish this was face paint, and some nights I used to get a flannel and wet it and scrub my face because I couldn't believe it was not going to come off."
Christou had her first operation to reduce the internal bleeding and pain at age 6, and continues to go back to the hospital for additional surgeries. Each time, she has to travel from her home in London to Denver, Colorado, to see specialized doctors Wayne Yakes and Edward J. Hepworth.
Knowing how expensive treatment can get, Christou and her parents created the Butterfly AVM Charity, and has raised over £175,000 for research and medical fees for other sufferers. And in 2013, she won an award for the most inspirational child in the United Kingdom, presented by Prince Harry himself, an experience Christou calls "unbelievable."
"At the time I didn't feel as if I had done anything special," she tells PEOPLE. "I was just trying to get on with my medical condition but wanted to help raise money and awareness about my illness."
"Prince Harry was such a lovely man, he was very kind and wanted to know all about me and my charity. We spoke about his nephew George who has the same name as my Dad and that George has the same birthday as me! I must say he is more handsome in real life than on TV!"
Now she's back to vlogging and interacting with all of her thousands of followers.
"[It's] unbelievable!" she says. "I have subscribers and friends who view my channel from around the world in over 100 countries. The majority of comments that I get are so nice and it makes it all worthwhile. I just love making people smile and happy and of course giving them a few make up tips along the way."
And she's looking forward to finding even more friends in the future.
"I just want to carry on vlogging and one day hope to have many more subscribers!" Christou says. "I hope that I can continue being as healthy as I can be, carry on doing well at school and pray that one day our charity can fund enough research so that we can find better treatments and a cure for all AVM sufferers around the world."