SANTA CLARA -- From the moment Delfin Santos Jr. was born, his military career was already a lifetime in the making.

His father, a World War II veteran for the U.S. Army, had a dying wish for his youngest son and namesake to enlist and carry on the family tradition.

Delfin Sr. held on just long enough: On the day he died in December 2006, the junior Santos left for boot camp.

"We promised," said sister Madeleine Santos, who followed her brother in enlisting.

Spc. Delfin Santos Jr., who grew up in San Jose and Santa Clara, was one of three soldiers killed Saturday in Zabul province in Afghanistan when a "vehicle-borne improvised explosive device," attacked his unit, according to the Department of Defense. He was 24.

Santos approached his Army career with zeal, his sister said.

"My brother was all about the military," Madeleine Santos said. "He loved it. He did what he needed to do as a soldier."

His enthusiasm was infectious: Madeleine enlisted just as her brother graduated from boot camp, and together they were deployed to Iraq in 2007. The duo was unique enough that they were featured in an Army newsletter as they carried out their assignments in Baghdad, which fell to Coalition forces 10 years ago.

"When we were both PFC (Private First Class), there was a news item written about us being brother and sister out there," she said. "He's always been my inspiration. He's the kind of guy who motivates you."

Santos was born in the Pampanga province of the Philippines and moved to the Bay Area in the early 1990s to live with his father, a combat veteran in San Jose. He attended local schools in San Jose and Santa Clara before returning to the Philippines for high school. He is survived by two sisters and 13 half-siblings from his father's first marriage.

He had just graduated from the prestigious Saint Dominic Academy in Bulacan when his father, by now an elderly man who knew his time was limited, summoned his youngest daughter and son back to the United States.

"My dad said, 'I want you to join the Army, it's going to be the best for you,' " Madeleine Santos said. "(Delfin) wanted to be like my dad."

Santos' career took him from South Carolina to Fort Lee, Va., then to Germany. After a 15-month tour in Iraq, he went to Fort Sill, OK., later reclassifying as a cavalry scout, a title he held when he died. He was assigned to the 5th Squadron, 7th Cavalry Regiment, 1st Armor Brigade Combat Team, 3rd Infantry Division, based out of Fort Stewart, GA.

Madeleine Santos, now an Army reservist, last saw her brother in person when he went on leave last July before his second overseas deployment -- this time to Afghanistan.

"He kept working out while he was on leave. He wanted to get the highest (physical training) test," she said. "He was always on track."

Santos was eyeing a post-Army career, but even that vision revolved around his military life. He aspired to use the G.I. bill to become a psychologist and help his fellow servicemen returning home from duty.

"He wanted to help people with PTSD," his sister said, referring to Post-Traumatic Stress Disorder.

While overseas, Santos kept himself busy with books, many about psychology, some on audio CD that came via care packages from his family in Santa Clara.

He never received his last package, which was still on its way.

Madeleine Santos recalled asking him what he wanted via email and Skype.

His requests were modest: A bottle washer, antibacterial soap, laundry detergent. And pistachios. His sister said after a mission he would fall asleep munching on pistachios and watching a movie.

Madeleine Santos also remembered the last conversation she had with her brother, via Skype, in what turned out to be his final hours.

"I spoke to him Friday, and he died the next morning," she said, fighting back tears. "He told me how much he missed being home."

As the family mourns him, the sister is looking to him one more time for inspiration.

"He's telling me to be tough right now."

Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.