Sebastian’s Legacy
Sebastian Daniel Guerra — A Heart That Gave, A Light That Shines Forever
Sebastian was funny, handsome, and full of charisma—the kind of child who could walk into a room and make everyone smile. He dreamed big, loved learning about U.S. presidents, and often reminded people to lead with kindness, proudly saying he had a “community heart.”
He was known for leaving sweet, witty notes for his mom—once writing, “A butterfly doesn’t need to be told that it’s beautiful, it just is,” and joking, “Are you a vegetable? Because you look like a cute-cumber!” His humor, creativity, and big heart made every moment with him unforgettable.
Sebastian loved creating YouTube videos with his sister Carolina—from ice-bucket challenges and interviews to silly dance reels that filled their home with laughter. His favorite video games were Minecraft and Fortnite, and he loved playing Uno with his family. He also enjoyed camping at the river, going to the beach, and swimming every chance he got. Music was always part of his joy—he loved dancing to “It’s About Damn Time” by Lizzo and “Bad” by Michael Jackson.
He adored making Halloween snack bags for other children at CHOC Children’s Hospital, where he was known for his big smile and his love of Rice Krispies treats—his favorite hospital snack. His favorite meal was always breakfast: bacon, eggs, and hash browns.
Sebastian worked hard in taekwondo, earning his orange belt and proudly showing off his medal. He had a love for TikTok dances, jokes, and trivia, and could name every U.S. president in order by heart. He dreamed of becoming a famous YouTuber, working alongside his dad at his company, and even made his own business cards. He once declared that he would become President of the United States at 35 years old—and everyone who knew him believed he could.
Sebastian’s favorite color was green, his favorite ice cream cookies and cream, and his favorite animal pandas. He loved cuddles with his mom, working with his dad, spending time with his grandparents, and pranking his Auntie Kristen. He always looked up to his Uncle Michael and loved caring for his younger cousins, proudly saying that because he was the oldest, it was his job to take care of them.
Sebastian was surrounded by love—his mom, Katherine Mosier; his dad, Miguel Guerra; and his siblings, Carolina, Diego, Miguel Jr., and Abby. His best friends, Jackson and Ryan, shared countless memories with him—from arcade games to movie nights—always filled with laughter and joy.
On his 10th birthday, January 17, 2024, Sebastian was diagnosed with Diffuse Midline Glioma (DMG)—an aggressive and currently incurable brain tumor. Doctors told us he might have only one year left, two if we were lucky. But Sebastian faced his diagnosis with courage, humor, and faith.
He underwent 30 rounds of radiation, two brain surgeries, and bravely battled through seizures and weakness caused by the tumor. Despite it all, he never complained. He loved his doctors and nurses—even proposing to a few—charming everyone at CHOC Children’s Hospital in Orange, California.
Sebastian joined the DIPG-Vax clinical trial, offering hope not just for himself but for children in the future. For nearly seven months, he was symptom-free. When the tumor returned in December 2024, he continued to fight with grace, courage, and unwavering faith.
With the help of Make-A-Wish, Sebastian saw one of his biggest dreams come true with a trip to Washington, D.C., where he received a private White House tour—an unforgettable experience for a boy who loved history and presidents. His other dream—to visit Paris, France, and see the Eiffel Tower and Mona Lisa—came true thanks to the generosity and love of family and friends who made that special journey possible.
Sebastian was also baptized, his love for Jesus shining as a guiding light that inspired everyone around him. He celebrated his 11th birthday surrounded by family and friends—a milestone his doctors once thought he might not reach. Just a few weeks later, on February 6, 2025, our brave boy passed away, surrounded by love.
Even in his passing, Sebastian gave the greatest gift of all—the gift of hope. He donated all six of his brain tumors to research through the Gift from a Child Foundation, so that one day, other families may hear the words “there is a cure.” His donation continues his mission of kindness and compassion—proof that even in the hardest moments, his heart remained devoted to helping others.
We miss our Sebastian every single day, but we see him everywhere—in everything green, in every panda, in the sparkle of the ocean, and in the laughter of children chasing their dreams. His courage, faith, and love for life continue to guide us.
Sebastian Daniel Guerra was, and always will be, our light—a boy with a community heart who changed the world with his smile.
Our Donation Story
When our son, Sebastian Daniel Guerra, passed away, we were heartbroken—not just from losing him, but from everything cancer had taken from his little body. I didn’t want that terrible disease to be a part of him any longer.
That’s when Rady Children’s Hospital told us about Gift from a Child. For the first time, we felt that something good could come from something so devastating. The idea that Sebastian’s tumors could help researchers find answers—maybe even a cure—gave us comfort and purpose in our deepest grief.
Sebastian always said he had a “community heart,” and through this donation, that heart continues to give. Knowing that his six brain tumors were sent to researchers working to defeat Diffuse Midline Glioma (DMG) helps us believe that his passing was not in vain.
Our family is so grateful that his life—and even his final act—can bring hope to others. And through our faith, we know that one day we will have eternity with one another—healed, whole, and together again.
We hold on to the belief that because of brave children like Sebastian, one day no family will have to face the monster that DMG is.
