LOUISVILLE, KY (WAVE) - The Walker family was spending a warm, sunny day at the pool in August 2015.
Their 13-year-old son, Matthew, was having a blast -- until his parent noticed something strange. He had a lump on the side of his neck.
From that moment, their lives would never be the same.
Doctors found that Matthew had leukemia, a form of blood cancer which both his grandfathers also had.
The seemingly never-ending procedures began immediately.
Matthew's father, Dion Walker, a U.S. Army Veteran, documented their journey of survival. From the days when Matthew was delirious and exhausted, to the days when his determination to live shined through.
The Walkers, who live in Hardin County, would travel to Louisville and Cincinnati for treatments.
Doctors told them Matthew needed a bone marrow transplant.
"To my brave young recipient," Matthew read off of a letter. "Hope everything is going well and you're resting.
"I cannot imagine myself fighting as hard as you," the letter said.
Matthew is now 15. He doesn't remember much of those dark moments lying in a hospital bed. But he remembers the moment that letter was delivered just two weeks after his bone marrow transplant.
The life-saving procedure was thanks to that same stranger who'd sent him that letter.
"I wouldn't be alive necessarily," Matthew told WAVE 3 News. "At all."
"It's hard to think about those times," Matthew's mother Angela Walker said. "But we are very, very thankful that he's still with us."
Matthew now has his donor's blood type and his DNA. But it wasn't until one year after the transplant that the Walkers would get to see Billy Santoro's face.
"We cannot begin to thank you for what you did for our son here," Dion Walker said in the Facebook video while they Skyped with the 21-year-old college kid.
Matthew didn't have a clue what his donor looked like until that point.
"I thought about a beard, that's the only thing I thought about," Matthew said.
"He lives in New Jersey!" Dion Walker told his Facebook friends watching the Skype interview. "New Jersey!"
"When we talked to him, it's like he fit right in with our family," Angela Walker said.
Matthews parents would have to wait until Friday to meet Billy in person. Until then, Matthew's mom thought about what she'd say.
"I don't know..." she said. "I don't know. I just want to hug him."
And that's exactly what she did as she ran to him when he arrived at the airport. There were hugs, tears and many thank you's.
"Come here my baby," Angela Walker told him. "Oh, my lord."
The Walkers weren't the only ones who couldn't wait for this moment.
"Being able to give a young man his life back to him, it's just surreal," Billy said. "It really is. I'm happy I could help."
Turns out Billy is a triplet. He brought his brother along for the trip too.
"We gained two sons and a daughter and a new family," Dion Walker said. "You couldn't ask for anything more than that."
On Sunday, it was time for the two new blood brothers to be face to face.
These two now share the same blood type. Same DNA.
"I wouldn't be alive necessarily. At all," Matthew Walker said.
He has a lot to be thankful for.
"I always considered my luck very high. If not I've already used it all," Matthew said. "I don't have much luck left"
By luck, he means 21-year-old Billy Santoro, once a complete stranger from New Jersey. Billy gave Matthew a chance at life by donating bone marrow - an almost perfect match.
The two shaved their heads together Sunday at a Clip for Kids event, helping others who share at least part of the story.
United by blood and by both their wills to tell cancer -- that love is stronger.
If you would like to get swabbed and potentially save someone's life, visit bethematch.org for a free mail-in kit.
The search for a bone marrow donor began as doctors told the family that because Matthew is bi-racial, finding a match would be even more difficult. Matthew's immediate family, including his two older brothers, weren't a match.
But finally, in January 2017, they got the news they'd been waiting for. A donor from New Jersey scored a 9 out of 10 match with the young teen.
The family was only told the donor was a 20-year-old man -- not even old enough to have a drink.
"We were stunned," Matthew's father, Dion, said.
Matthew then had to go through additional rounds of chemotherapy and full body irradiation to kill the cancer cells before he received the bone marrow transplant.
Dion Walker recorded the moment of the transfusion. A small pouch containing the life-saving liquid was hooked up to Matthew's intravenous tubes. His mother couldn't stop the tears as her son joked about the iron-like taste.
Matthew is now cancer free and eagerly playing paint ball, a sport which he was told he couldn't participate in during his treatments.