Garrett Doyle was only one when his father was killed in the Sept. 11 terrorist attacks on the World Trade Center, but the loss would have a profound effect on his life.

In elementary school, teachers would tell his mother they were concerned about his drawings of the twin towers on fire or a poem about Osama bin Laden killing his dad.

At 12 years old, Garrett Doyle thought he found his purpose in life: Kill the next Osama bin Laden to avenge his father's death.

"I was so angry," Garrett Doyle said. "They stole my dad."

The Quebec-raised boy started training with the goal of one day becoming a Navy SEAL, the elite U.S. special forces team that killed the leader of al-Qaida, the terrorist group that carried out the 9/11 attacks in 2001.

His father, Frank Doyle, was 39 years old when he died.

His mother, Kimmy Chedel, didn't hide the truth from her son and her daughter, Zoë Doyle, about what happened to their father and who was to blame. 

Through his teenage years, Garrett Doyle trained every day, his eye always on the SEALs. As he was about to head off to Elon University in North Carolina in 2017, he had a heart-to-heart conversation with his mother.

She implored him to find a different purpose -- to stop dreaming about becoming a SEAL. She wanted him to live a typical student life. 

He relented.

"By becoming a SEAL, I wouldn't be protecting my family, I'd just be hurting them," the now 21-year-old said.

"That goal motivated me and helped me, to be honest. I thought I could do something better for the world by killing terrorists, but when I became older I realized I could do other things to make the world a better place."

The family has found a way to heal, somewhat, through a prolonged effort by Chedel to keep her husband's memory alive. In May 2002, she started "Team Frank," bringing together family and friends with the initial focus on sports.

The idea was to create memories for her children, who were one and two years old when their father died.

"I don't know if all the memories I have are actual memories or if it's more what people have told me and what I've seen over the years," said Zoë Doyle, now 22. "But either way I do feel like I have memories with my dad."

One night stands out: she remembers sitting on her father's lap looking up at the moon and the stars.

Shortly after 9/11, Chedel and a filmmaker friend made a family video of her husband. There are videos of Frank's last Christmas and final Halloween with the kids, some of it set to the Beatles, one of his favourite bands.

"I feel like I know him," Zoë Doyle said.

Frank Doyle was born in Detroit, Mich., went to college in Maine, completed his master's at NYU and worked his way up as a trader on Wall Street to become a senior vice-president at Keefe, Bruyette and Woods. 

Twenty-three Canadians died in the 9/11 attacks. Frank Doyle is considered the 24th Canadian, Chedel said, because his parents are from the Ottawa Valley, she is from Quebec and the Canadian consulate played a crucial role in helping her family in the aftermath.

He played a lot of sports growing up and went to college on a hockey scholarship. Later he'd find passion pushing himself as a runner and a triathlete. 

On Sept. 11, 2001, after a hijacked plane struck the south tower of the World Trade Center, Frank Doyle called his wife several times. 

"You have to promise me every day for the rest of their lives you'll tell Zoë and Garrett how much their papa loves them," Frank Doyle told her at 9:22 a.m., his last call.

In November 2001, Chedel, then 37, moved to the family cottage in the Laurentians and later to Montreal. She soon began seeing a grief therapist with the kids in tow.

"She said to me 'you need to pick two days a year to honour your husband, and the other 363 days you need to live in the present for these children -- a happy mommy makes happy children," Chedel said.

Since then, she has tried to be relentlessly positive. The team has been getting together every year in New Jersey to run a road race and in Quebec for a triathlon.

Members of the team wore Team Frank shirts on the summit of Mount Kilimanjaro, at Mount Everest base camp, and on a swim to Alcatraz Island in the San Francisco Bay, along with numerous triathlons and marathons.

The stories would be shared on a private Facebook page, much of it done to show Zoë and Garrett how much they are loved.

They would need that support as death after death befell the family.

In 2015, Chedel's father died. 

"He was like another dad to my kids," she said.

About five years after Frank Doyle died, Chedel fell in love again with a man named Francois-Claude Paquette, who also went by Frank.

In November 2018, Paquette was diagnosed with colon cancer. He died 100 days later on Valentine's Day in 2019. He was 44 years old.

"If that didn't kill me, I don't think anything will," Chedel said.

Then Chedel's mother died on May 29 of this year.

Death has forced the siblings to grow up quickly. 

"I'm getting used to the people I love dying," Garrett Doyle said.

Back in 2013, with the kids quickly maturing, the family went to Costa Rica.

"I decided that I wanted to start doing trips with meaning and I wanted my kids to realize that they're fortunate, and that we need to give back," Chedel said.

So they brought school supplies to an elementary school in a remote Costa Rica village. They've also brought supplies to remote areas of South Africa, Rwanda and Kenya. 

In 2017, the family launched Team Frank Africa, a Canadian not-for-profit that has since built four preschools in remote South Africa. They hope to build 26 more.

"I think by having this team and being supported by love and friends and having a goal has been my saviour," Chedel said. 

Zoë Doyle graduated from Elon University this year where she majored in global studies with a focus on Africa, the same program her brother is now taking. 

She is set to move soon to Cape Town in South Africa where she will launch a bikini company. She plans to use part of the sales proceeds to support Team Frank Africa.

Garrett Doyle has begun his senior year in college, is working on becoming a personal trainer and hopes to one day run his own gym and volunteer as a firefighter.

The siblings are not entirely sure where they'll end up, but both are grateful for growing up in Canada.

"I like that we were sheltered when we wanted to be," Garrett Doyle said of growing up outside the U.S.

"I've met lots of people my age in the States who lost a parent in 9/11 and there's lots of anger," Zoë Doyle said. 

"Growing up in Canada we were kind of removed from the attention, so we focused on remembering our dad."

This report by The Canadian Press was first published Sept. 10, 2021.

Liam Casey, The Canadian Press