The toddler became the youngest person in Scotland to be diagnosed with cancer … just 12 hours after he was born.
His tiny body had to endure gruelling chemotherapy and a complex operation to remove a tumour on his liver when he was months old.
Evan's shocked parents watched in awe as the baby battled his condition with a smile on his face.
Now in remission, Evan is thriving, and his family - including his doting eight-year-old sister Jorja - are looking forward to celebrating a Christmas with him that they feared they might never see.
Dad Scott said: "Evan is a very happy wee boy. His personality is starting to shine through and he loves dinosaurs and cars.
"He is an inspiration to us all and we are looking forward to being able to spoil him and Jorja this Christmas."
Scott and wife Lorraine, who are both mental health nurses at the Gartnavel Royal Hospital, Glasgow, were overjoyed when Evan was born on November 18, 2011 following a straight-forward pregnancy and birth.
But, moments after he entered the world at 6lb 9oz, a midwife at the Princess Royal Maternity Hospital, Glasgow, raised concerns when she noticed swelling on his abdomen. She alerted a doctor and a series of scans were arranged.
Evan was then transferred to Yorkhill Royal Hospital For Sick Children.
Scott, 43, said: "We were concerned but not overly worried because it never crossed our minds for a second that he could have cancer … never in a million years."
But hours later, Scott and Lorraine, 40, who live in Lennoxtown, Dunbartonshire, were called into a room in the hospital where two doctors and a nurse were waiting to deliver the crushing news.
Scott said: "The doctor was very matter of fact and said, 'We have found a mass on Evan's liver'. My wife said, 'Like cancer?' And the doctor replied, 'Yes'.
"It is hard to describe what went through our heads, it is a bit of a blur."
Evan then underwent a range of tests to establish whether or not the cancer had spread.
Scott added: "We knew his chances were significantly better if the cancer was contained.
"When we found out it hadn't spread, that was a strange day - skipping out of hospital relieved that my newborn son 'had cancer only in his liver'."
Their son was diagnosed with hepatoblastoma and became the youngest person in Scotland to develop cancer and the youngest in the UK to develop liver cancer.
He started chemotherapy through a central line in his tiny body and was later taken to a hospital in Birmingham for an operation to remove the large tumour from his liver.
Scott said: "I recall looking at him and he was so small, wishing I could take it from him, and wondering how he had the strength to fight.
"Children are so resilient, he is remarkable.
"But there were about three occasions when I was looking at him thinking we were losing him, because he was so ill.
"The worst occasion was when he developed septicaemia from a bug in his central line."
Thankfully, Evan managed to fight back each time.
Said Scott: "He was either very seriously ill or smiling away, wanting to play.
"This is the thing about children, there is no feeling sorry for themselves."
Evan was treated in the Schiehallion children's cancer ward in Yorkhill and Scott and Lorraine became close to other parents whose children were also battling the disease.
Scott said: "Some of the parents with older children would comment on how tiny Evan was and say it was terrible and ask how we were coping. But our hearts went out to them.
"Because Evan was so young he did not fully understand what was going on.
"He would get upset during some of the procedures but we were able to settle him and, minutes, later he was calm again.
"But I saw the fear on some of the older children's faces and heard them screaming when doctors went into the rooms.
"Lorraine managed to breast-feed Evan for three months, for which she was commended, but she couldn't manage much longer and felt so helpless. But she coped amazingly well.
"We just had to, for Evan's sake and for Jorja.
"There were times when I would be driving home in the car screaming. It was a release.
"But you find the strength. You don't know you have it in you, but you find it somehow."
Today, Scott and Lorraine could not be more proud of their little boy and Jorja, whose life was also turned upside down.
They said they could not have coped without the fantastic support of family, friends and their community, who helped them raise £5,000 for children's cancer charity Clic Sargent.
Scott added: "Christmas is a wonderful time of year for all families and we are no different.
"Evan is starting to understand a bit about Santa and presents, which is lovely.
"When you live through a child being so seriously ill, it changes your perspective on life.
"You don't sweat the little things any more and you cherish the special times you have together."