SEAL from Cape devoted to the end

But a few weeks ago, Houston gave the flag to the person for whom he had always carried it. “I hope you let her fly in the backyard and have a toast every now and then,’’ he wrote in a note, held in the flag’s folds, to his mentor and father figure, Christopher Kelly of Osterville.

Houston, 36, a graduate of Barnstable High School who was living in Chesapeake, Va., died Saturday in the rugged mountains of eastern Afghanistan. He was on his fourth tour of Afghanistan when insurgents shot down a NATO Chinook transport helicopter carrying 30 American troops, including members of Navy SEAL Team 6, members of which carried out the Osama bin Laden raid in May.

Friends and family spoke yesterday of a skilled athlete, a loyal friend, and a loving father, brother, and son who protected those he knew and those he did not. Houston was a handsome, gregarious athlete, they said, who had wanted to be a SEAL since he was a toddler.

“This is what he had always dreamed of doing,’’ Kelly said. “He was fiercely loyal. He fought for everyone he loved.’’

Houston, who grew up on Cape Cod, received a Purple Heart medal, two Bronze Stars, and more than half a dozen other decorations during 16 years in the Navy. His body will be returned to Chesapeake, where his wife, children, and mother live. He will be buried in Arlington National Cemetery.

“As a mother, I’d practiced this in my brain for years, and I thought I’d be all New England stoic,’’ said Janette Brown, who said she collapsed when a solemn officer in white gloves knocked on her door at 8:30 a.m. Saturday. “No matter how much you think about losing your son, you’re never ready.’’

The single-parent family had already lost a daughter, their middle child, Miranda, to ovarian cancer in 2005. When doctors said Miranda had less than a week to live, Houston took leave from the Navy to visit. The former high school linebacker carried his younger sister’s frail body to the hospice garden, where she dipped her feet in a fountain, looked up at her big brother, and spoke for the first time in weeks.

“She waited until he was there with her before she passed away,’’ Brown said. “He would have done anything for her.’’

Houston made his mark by forming close relationships and maintaining them, Kelly said. He struck up a friendship with Houston when the high school football captain began dating Kelly’s daughter.

The men found common ground in the military, and soon, Houston considered Kelly his surrogate father.

Kelly would pull out his photo albums from Vietnam - Houston could name every plane that flew in the war - and when Houston enlisted, he returned home with war stories and photos of his own.

Houston finished his SEAL training in 1999 in California and returned to the East Coast, settling in Chesapeake.

During his career with the Navy SEALs, he worked in an Iraqi prime minister’s personal security detail and participated in more than 100 capture and kill missions.

On a recent tour of Afghanistan, grenade shrapnel pierced Houston’s legs as he dashed toward a fellow SEAL, attempting to save him from enemy fire during a close-range ambush.

The attack left him with scars on his ankles and earned him the Purple Heart, the presidential decoration for service members killed or wounded in action.

The grenade attack was not Houston’s first brush with injury. The day before his senior prom, Houston broke a bone in his back in a motorcycle accident and spent the dance - where he would have been crowned prom king - lying in a hospital bed. That night, limos rolled up to the hospital, teenagers traipsing through the hallways of the pediatric ward in tuxes and evening gowns, looking for their friend.

He graduated from high school in a wheelchair. Six months later, he passed his Navy physical.

Friends supported Houston because they knew he would do the same, they said.

When Houston and best friend Joe Kennedy spotted an elderly woman with blown-out tires on her car, Houston insisted they pull over. When she said she was waiting for AAA, Houston said they would wait with her.

Houston never told anyone about it, Kennedy said, because he never wanted praise. He just liked helping people.

As captain of the football team, Houston was the one who could rally players when coaches failed to, coach Paul Demanche said. Houston’s smile disarmed tough-guy personas and left coaches walking away chuckling.

“His personality and his smile were infectious,’’ Demanche said. “Even if you had to coach him or criticize him, he’d get this big grin.’’

Kelly said he will fly Houston’s flag in the back yard as requested, a reminder of the son he never had.

Globe correspondent Ben Wolford contributed to this report. Laura J. Nelson can be reached at lnelson@globe.com.