He wouldn't have to spend his favorite holiday, Halloween, in the hospital.
But then he thought about other kids who would. He especially worried about his roommate from the previous night at California's Kaiser Permanente Oakland Medical Center. When he learned that the boy would likely be in the hospital for Halloween, Nico had an idea.
"Can we get him a costume?" he asked his mother, Marlene. "Can we get costumes for all the kids?"
With that question, Nico – diagnosed a year ago with brain cancer – started a Halloween-costume campaign that got his whole family involved. His dad, Raul, helped Nico organize a costume drive at C&C Automotive Refinishing, the automotive body shop he owned.
Courtesy of Marlene Castro
On October 4, Nico, in costume as a Star Wars storm trooper, presided over the drive as about a hundred people came in with Halloween-themed books, games, toys, movies and costumes. Nico raised an additional $1,200 in cash and, so far, has a collection of 166 costumes that were purchased or donated – including Buzz Lightyear, Sleeping Beauty, pirates and firemen – and that he plans to hand out to young patients the morning of Oct. 31.
For Nico, the motivation is very simple. "The kids in the hospital," he says, "they can't go trick-or treating."
Nico's giving out costumes will help the other kids by "providing them with a sense of normalcy," says Carla Delemos, a child life specialist at the hospital. "Even though he's going through all these challenges with his medicine and his treatment, for him to be able to think about other kids is such a wonderful attribute."
As for his own Halloween get-up, Nico will dress up as the Dark Knight, similar to his Batman costume last year. The reason: He wants something that covers his head, which is now bald as a result of chemotherapy.
"He's very self-conscious about not having hair," Marlene says of her son, who took pride in his jet-black hair. She says her son's courage throughout his illness, which has involved surgery, radiation and blood transfusions, is an inspiration.
"He's a very positive, spunky little boy," she says about her youngest of three children. As for his costume-drive idea, she says, it's typical of the boy who loves riding his bike, his dog Willie, dancing to Michael Jackson and superheroes.
"It's amazing that at such a young age he thinks this way. He's always thinking about other people," Marlene says. "He's got a heart of gold."
Courtesy Dave Lourenco
One recipient of Nico's generosity is 6-year-old Nolan Lourenco, who receives weekly chemotherapy at Kaiser Permanente for a brain tumor.
"He was handing out costumes and he gave me a fireman costume," says Nolan of his new friend Nico. Nolan proceeded to put on the get-up and showed it off to everyone on the hospital floor.
Says Nolan: "I love my costume!"
Costume donations can be sent to or dropped off at C&C Automotive Refinishing, 860 San Mateo Ave., San Bruno, CA 94066
Know a hero? Send suggestions to email@example.com. For more inspiring stories, read the latest issue of PEOPLE magazine