In Vietnam, where he probably was fathered by an American serviceman, Peik Larsen was called a "bui doi," one of the mixed-race orphans who became known as the "dust of life."
Had he stayed much longer in a Da Nang orphanage, he might never have lived to enthusiastically enjoy the full life he made in the United States. When he was an adult, no one who saw him fill a room with his smile, spirit, and irreverent humor would guess that he weighed but 12 pounds when he was 10 months old and that en route to his new home in Cambridge he detoured to a hospital so doctors could treat him for viral pneumonia and hepatitis B.
One of 10 siblings, a half-dozen of whom were adopted, Mr. Larsen brought unchecked optimism to a life that saw him work as a commercial king crab fisherman in Alaska, teach gymnastics in San Francisco, and manage operations at JetBlue locations. Then he returned home, finished college in his 40s, and landed a job that was to begin this week, teaching in a Cambridge school system where as a youth his energy dwarfed his discipline.
"I never thought about our life without him," said his wife, Emi Fujiwara Larsen. Their twin sons, Kai and Ren, turn 5 in October. "Maybe when someone has that big of a personality and that much light you don't think it's going to run out. How quiet our house is, how still our life is without him. He filled every corner of our house."
On July 23, she returned from work to find Mr. Larsen ill. He told her he was experiencing food poisoning symptoms, and he died a few hours later while they were sleeping in their Belmont home. Mr. Larsen was 42 and his relatives are awaiting word from the state medical examiner's office, which told the family that tests could take a year to complete.
"Peik was spontaneous and creative and utterly unique. He was always coming up with crazy stuff that made life more fun," his sister Britta of Cold Spring, N.Y., said in a eulogy at his July 30 funeral in First Church in Cambridge, Congregational.
At the service, Mr. Larsen's friends recalled that on those rare times when he didn't run into someone he knew during any Cambridge outing, he ended the night with a few new friends. Everyone seemed drawn in by Mr. Larsen's way of turning the ordinary into something extraordinary.
"With Peik, every event yielded fabulously funny stories, like souvenirs, and I just can't imagine our future without him," Britta said.
Those who gathered to celebrate Mr. Larsen's life left with a recipe, printed on the funeral program, for the extravagant meal he created for a family gathering on Nantucket, from which he returned a couple of days before he died. And they listened to his sister Anika, a Tony-nominated actress on Broadway this year, sing the Sting song "Fields of Gold."
Hundreds filled the spacious sanctuary, standing in the back and spilling into hallways when the pews had filled. In certain respects, such a large crowd might be expected for someone as affable as Mr. Larsen.
"Peik sort of wore Cambridge on his sleeve," Britta's husband, Patrick, said in an interview. "He was just born with this sense of wanting to create a good time and have a good time, and to share that with people."
That excitement and affection extended beyond Mr. Larsen's expansive circle of friends to those with whom he worked, and those to whom he was closest. His work may have brought him as far away as Alaska, but he returned to Cambridge for college, working at the Kendall Hotel while finishing a bachelor's degree at Lesley University. After a year as an ESL instructor at Vassal Lane Upper School in Cambridge, he was hired to be a sixth-grade history teacher at Rindge Avenue school, where classes began without him this week.
"I was very excited to have him join us, and he was ecstatic," said Ralph Watson, principal at the Rindge Avenue Upper Campus. "He was one of those people you meet and know that he's going to be an incredible teacher. The kids he would have taught lost out by not having him."
His father, Rikk of Cambridge, said Mr. Larsen had already shown how he could combine fun and discipline, and learning and love with his twin sons.
"He became a better father to his kids than I was to him," he said. "I learned a lot from him, and the lessons he taught me about fatherhood will make me a better grandfather and male figure in their lives."
Peik Irgens Larsen never learned the identity of his biological parents, though in 1996 he returned to Vietnam with his mother, Pamela Hughes of Pawtucket, R.I., and his sister Kari of Larchmont, N.Y., who also was adopted from Vietnam.
"An incredible thing about that Vietnam trip was how Peik made those he met love him there, even though as the dust of life, he was not supposed to be loved," Mr. Larsen's mother said in her eulogy.
She added that with his death, "there is a massive hole in our family that will never be filled. Dates for family events were picked based on Peik's availability because it was not a party without Peik."
In a family with six adopted children hailing from Vietnam, Cambodia, and El Salvador, there was no shortage of names that were difficult to spell and challenging to pronounce. Mr. Larsen turned that into an excuse for fun, too.
"When someone would struggle with his name, he'd say, 'It rhymes with cake. Like Birthday Peik,' " his brother Trygve of Lynn said in a eulogy. With Twitter and Instagram, "fittingly, his handle was @PeikLikeCake."
In 2008, Mr. Larsen married Emi Fujiwara and not long after they had twin sons, Kai and Ren Fujiwara Larsen.
"For him, being adopted, having two kids who looked like him, who had his blood, was meaningful," she said. "It really changed him."
In addition to his wife and sons, his mother and father, and his siblings Kari, Anika, Britta, and Trygve, Mr. Larsen leaves three other brothers, Tage of Chicago, Jens of Brainerd, Minn., and Christian of San Salvador; two other sisters, Siri Garcia of Queens, N.Y., and Nissa of Manhattan.
After a particularly big storm last winter, Mr. Larsen came in from shoveling and announced that the snow bank in front of the house looked like an alligator. He enlisted Emi and Ren and Kai in the effort and they shaped the snow into a 30-foot replica of an alligator that Emi tinted green with food coloring.
Whether molding snow into a temporary neighborhood landmark or engaging his young sons in the day's plans for visits to a park, Mr. Larson had a fervor for life that was irrepressible.
"At the end of the day, or at the end of an adventure, we would ask the boys what their favorite part was. My favorite part about Peik was the way that he loved Kai, Ren, and I so enthusiastically," Emi said in her eulogy.
"We would have followed him anywhere," she added. "We would have done anything with him, because he made everything more fun. Someone once asked me if I laughed every day, and we did. Peik made me laugh every single day."