A letter written by Kate Middleton to Fabian Bate, a young boy who passed away from cancer at age 12 earlier this month, is now giving his family comfort as they grieve the loss of their son.

The Duchess of Cambridge, 32, penned the heartfelt note — written on personalized paper from St. James's Palace — to Fabian in 2011 after the royal visited him at London's Royal Marsden hospital.

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Kate visiting Fabian in September 2011. (Photo Credit: Getty)

"I was touched by your strength of character and delighted to hear the news that one of your big sisters will be able to donate bone marrow to you later this year," wrote Kate in the note, which was later released to the public by the Bate family. "I will keep you and your family in my thoughts and prayers."

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Though it's now been three years since Fabian received his letter from Kate, his parents, Darrell and Lydia, still cherish her act of kindness and emotional words of encouragement to their youngest child.

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(Photo Credit: R/R)

“It gives us a lot of extra comfort that from the very top to the bottom he was loved and thought of," Fabian's father Darrell, 52, told the Daily Mirror, adding the letter "is very personal and special."

Following Fabian's death, a spokesman for Kate and Prince William released a statement sharing the royal couple's sincerest condolences to the Bate family during this difficult time. “The Duke and Duchess are sad to hear the news and their thoughts are with Fabian’s family," it read.