Freddie and Arthur were diagnosed with cancer just months after each other. Doctors discovered Arthur had a brain tumour and three months later, Freddie was diagnosed with sarcoma, a soft tissue cancer.
"The boys are like any other brothers," says Natalie, mum to five-year-old Freddie and two-year-old Arthur. "They love each other one minute and the next they are tumbling around fighting over toys and play fighting.
"They have a stronger bond because of what they have and are going through, and this will be really big for them when they get older."
The brothers are being treated at Great Ormond Street Hospital (GOSH).
"There are only two other cases of this ever happening with these two specific cancers within siblings, " says their dad Martin.
"There was a higher likelihood that Freddie could have developed the same cancer as Arthur, which we were warned about at the time, but to develop a completely unconnected cancer is not something that ever really happens."
With both Arthur and Freddie, their parents became concerned when they developed an ear infection.
"Arthur was unwell for a couple of weeks and we went to the GP in the morning. Martin was going to Paris for work that day," says their mum Natalie.
"By the afternoon Arthur was having an MRI at our local hospital, Watford General, and by the evening we were at GOSH. The next morning he was having 10 hour brain surgery. It was a lot to get your head around in such a short space of time."
"I left in the morning thinking nothing was particularly wrong and then went to GOSH and my world was crumbling, it had collapsed.," adds Martin.
"When Freddie started feeling poorly I had an awful feeling in the pit of my stomach again," continues Natalie.
" I just knew something wasn’t right. I can’t describe it, you just know. Freddie even said to me, 'Mummy, did you know I was getting poorly?' and I almost did. It is devastating."
A magical place
"The thing that is quite nice about GOSH is that we are this quite unusual family who have got this horrible thing going on and it's not normal. At GOSH it's not so unusual and they are used to dealing with children who have cancer," says dad Martin.
"They can deal with parents who are going through probably the most difficult thing you have to go through in your lives and they make you feel so positive about it."
"They are amazing people, all there to make your journey easier." says their mum Natalie.
Making the best of it
"We try and be positive and make the best of the situation," says Natalie.
"When Arthur was diagnosed we had to cancel a family holiday, so we bought bikes and took the boys out on lovely bike rides and have as much fun as possible in the confines of this new life we have.
"There is nothing we can do to change what life has dealt us, all we can do is change the way we react to it. We have a responsibility to make their lives as fun as possible.
"It can be very challenging, especially if they are on different wards. Another day we could be at home and a community nurse might visit. If you can get out, that’s great, but often we couldn’t."
Arthur’s treatment is now finished, and he will continue to have regular MRI scans and hearing checks.
This means he can have it at home, giving the family a bit more freedom.
A milestone that we are looking forward to is having Arthur’s central lines removed, which deliver drugs straight into the heart.
"The lines are restrictive, they mean they can no longer go swimming which they loved," says Natalie.
"The boys are very aware of them, and although they cope with them very well and are very careful, they do miss out on activity they’d love to do – playing in sand, the rough and tumble games two little boys would have."
The next steps for Freddie
"Although the boys finished their chemo on the same day, within an hour of each other, their paths are proving to be quite different," says dad Martin.
"While Arthur remains in remission for now, Freddie had an early relapse. This has been hard for so many reasons but for Freddie the hardest thing is his brother not having a wiggly like him."
"Having two children with cancer is really tough but having a brother to go through it with makes it less scary and normalises even the most surreal situations. However Freddie remains the most brave and lovable boy ever. When he had to have brain surgery which left a massive scar, it was ok because Arthur had one too."