Before his vocabulary included the words “stress” and “isolation,” Luke Jenkins felt both.

He realizes that now at 15.

But when he was younger, and he would watch his parents rush his little brother, Brayden, to the hospital, he knew only that he felt scared and that he didn’t understand enough about life and death to gauge the seriousness of the situation.

He knew only that sleep would not come easily that night, and that, until he knew his brother was okay, he wouldn’t feel much like eating.

“I might have even lost some weight,” the teenager recalls as we sit at a table in his home in Waterford, Va., in Loudoun County.

He is telling me this, not as a complaint, but as an explanation. In recent months, the eighth-grader has launched an online effort to help young hospital patients and their siblings. Really, though, he’s been working on it for years.

“I’ve been going through this my whole life,” he says.

In the forest of charities, what Luke has created is a seed barely starting to take shape. He isn’t sure what it will fully look like when it is done growing, but he feels certain it’s needed among those other trees.

It started off as a middle school class assignment. For a “Be the Change” project, Luke was supposed to come up with a way that he could contribute to his community. He says he knew immediately that he wanted his project to focus on children who end up in hospitals and their siblings who go through that experience with them.

Luke says his research revealed that music and games help relieve stress, so he thought it would be great to encourage people to donate gift cards to go toward movies, music and other forms of entertainment for those children. For his project, he collected more than $1,000 worth of gift cards from relatives and friends. In April, he and his mom delivered them to Children’s National Hospital, where Brayden had spent many nights.

Luke could have stopped there. But he didn’t. He took his concept further. He came up with a name, Brayden’s Buds, created Facebook and Instagram pages and recruited a 13-year-old friend to draw a logo.

The brightly colored image Lilly Soska created depicts a figure on each side of a person in a wheelchair. In it, Luke sees himself and his older brother, Carter, walking alongside Brayden. A large heart hovers in the space between them.

“That shows we’re loving each other and not hating each other,” Luke explains.

When they were younger, Carter and Luke would play board games with Brayden on the floor. He couldn’t move his own piece, so they would move it for him. He often won.

The boys’ mother, Carrie Jenkins, says Brayden doesn’t have a specific diagnosis but has “complex medical disabilities” that require constant care. As a newborn, he started having seizures. Then those seizures were accompanied by gastrointestinal and respiratory problems.

She says the family has a strong support network in neighbors and the boys’ grandparents, but even so, just like many parents of children with disabilities, she and her husband, Jeremy, often worried about whether they were giving enough of themselves to their two healthy children. Luke was 2 and Carter was 4 when Brayden was born.

“I feel like sometimes Luke and Carter got the leftover version of us,” Carrie says. “Even just us having unfair expectations of them to sit there quietly in the hospital for hours. That’s a lot of expectation to put on a kid.”

“It seems like a minute is an hour in the hospital,” Luke says.

I ask him how many nights Brayden has spent in the hospital. He doesn’t even try to guess.

“Too many,” he says.

“A lot,” his mother adds. “A lot.”

She says she didn’t know that Luke was working on that school project until he started collecting gift cards. Now, she helps him post on social media and keeps track of the donations. A few days before Christmas, she and Luke took about $2,500 more in gift cards to Children’s National Hospital.

Jessica Miley, who is the chief operating officer for the hospital’s foundation, says it takes more than just medical care to help children heal.

“What Luke is doing is creating opportunities for kids to be kids,” she says. “He’s doing exactly what we need.”

She says those donations come at a time when the hospital is taking care of 316 families and likely to be at capacity through Christmas. Hospitalizations are stressful for the entire family, she says, and with that in mind, the hospital offers programs, including art, music and pet therapy, for patients and their siblings. But the gift cards will allow those children to get video games, toys and other forms of entertainment that are specific to their interests.

Miley says she hopes to meet Luke one day: “We’re so grateful for all the donations, but certainly what Luke is doing is remarkable.”

Luke speaks honestly about the sacrifices siblings of children with chronic illnesses sometimes have to make. He has missed out-of-town basketball tournaments, his friends have sometimes made memories without him and his family rarely travels.

But he also smiles when he talks about the small DVD player his mom used to pull out during many of those hospital visits. “The Lion King” was one of their favorite movies. Brayden can’t talk, but they know he enjoyed it, too, because he would moan until the singing started. Then he would grow quiet.

Luke recalls once seeing his mom slip that DVD player to another young patient, a girl who was sharing Brayden’s room. She was crying and alone because her parents and brother were also hospitalized after their church van was involved in a serious accident. Luke remembers going with his mother to Target to buy the girl some gifts, and then later, after she recovered enough to go home, playing with her at a Christmas party his family threw for the survivors of the accident.

Carrie says she’s glad her son has found a way to use those personal experiences to help his community. She also marvels at how, for him, turning that idea into action has seemed so seamless.

Luke says he hopes to eventually create an official nonprofit organization, bring in enough regular donations to sponsor a family each month and maybe expand the effort to other Washington-area hospitals.

As we talk about his goals, he stands next to his brother’s bed, alternating between holding his hand and rubbing his chest to comfort him. The 12-year-old is now in hospice care because his family has decided that his body cannot take any more stress.

Luke is old enough now to know what that means. His brother will not have any more hospital stays.

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