When Sean Walsh was 8 or 9 years old, his mother recalled, he'd knock on a friend's door in his San Jose neighborhood, and if the boy wasn't home, he'd ask for his sister. If she wasn't there, he would settle for whoever was home.
"So what are you doing?" he would ask the other kids' mom and invite himself in, said his mother, Cheryl Walsh.
"That was Sean," she said. "I can't tell you how many of the neighbors felt like he was a part of their families."
Many from the old neighborhood now mourn Walsh, as do others who knew him from Prospect High School in Saratoga, the Santa Clara Police Department's Explorer program and the California Army National Guard's 185th Military Police Battalion, 49th Military Police Brigade in Pittsburg, northeast of Berkeley.
The 21-year-old Army National Guard specialist was killed Nov. 16 in a mortar attack on his base in eastern Afghanistan's Khowst province, on the Pakistani border. It was about a month before his unit was to finish a yearlong tour and head home to the East Bay.
Born in Upland, Walsh moved to San Jose in 1994 with his mother, a pharmaceutical sales representative.
Besides being a goodwill ambassador to the neighbors, he was an avid skater and sometime surfer whose other interests included cars, dirt bikes and his German shepherd, Lena, who helped cement his plans for a career in law enforcement as a K-9 officer.
"He definitely loved that dog," said Brian Garcia, 21, who became fast friends with Walsh when both joined the Explorers four years ago. "He would do anything for Lena. He was so attached to her. Being a K-9 officer was a perfect fit for him."
Officer Bill Davis, advisor to the Explorer program, described Walsh as a "cross between Ferris Bueller and James Bond" and said "he had a certain charm about him." Walsh was dedicated to the program and spent hundreds of hours on community service projects, police training and ride-alongs with officers, Davis said.
"He had that drive, that intelligence," Davis said. "He was making all the right moves, all the right decisions to someday become a police officer, whether it was in Santa Clara or somewhere else."
Garcia said his friend was serious about law enforcement and joined the Army National Guard's military police unit at age 18 for the experience and competitive edge it would give him later. But Walsh was anything but all business, he said.
"He was a jokester, and his sense of humor fit in perfectly with mine," Garcia said. "For anyone having a tough day or not a good week, he would always find a way to get them smiling or laughing."
One of Walsh's favorite moves might be best described as not-so-fancy footwork.
"Whenever a song came on the radio, we'd step out and start dancing to it in the funniest way we could —people thought it was hilarious," Garcia said.
YouTube videos posted after his death show Walsh having fun even while deployed in Afghanistan. He is ever smiling and mostly mugging for the camera as he's shown in his off-time playing a ukulele, slurping noodles, lifting weights and dancing.
Sgt. Isabel Salazar, who posted a video with the message "You will be missed, but never forgotten," said Walsh parlayed his good nature into amicable relationships with Afghan security guards and villagers.
"Even though he couldn't speak their language and they couldn't understand ours, somehow he'd make friends with them and have full conversations with them," she said. "He was friends with everybody."
St. Andrew's Episcopal Church in Saratoga was packed for Walsh's funeral Dec. 3. Police, firefighters and soldiers joined with the fallen guardsman's friends and family — including his father, Kenneth Walsh of Ontario — at the church and at burial services at Oak Hill Memorial Park.
When he wasn't on a mission, Cheryl Walsh said, her son called or emailed her twice a day from Afghanistan. They often would talk about his plans for the future, which included trips to Disneyland, Hawaii and New York, earning a college degree and buying a used BMW.
Their last conversation, just hours before he died, ended the way they all did.
"We finished every phone call with 'I love you,' " she said. "That way, I always knew that if anything ever happened, those would be the last words we said to each other."