The kids, 11-year-old Olivia Nguyen, 8-year-old Edison Nguyen and 5-year-old Colette Nguyen, along with their grandmother Loan Le, died on February 16 as a winter storm paralyzed Texas.
Investigators say they believe the family was using the fireplace to stay warm after losing power the night before.
"We definitely want to get to the bottom of what happened. If we can even save one life, that will be worthwhile. So hopefully they can give us an answer," said Nathan Nguyen, the children's father.
He and their mother, Jackie, are separated and live in different homes.
Nathan tells ABC13 he has spent the past two weeks absorbing the shock, grief and anger over their deaths, and has been waiting to build the strength to search for answers.
"The anger is there you know," Nathan said. "Just because it's always like, 'Why did this happen?'"
The family was asleep when the fire broke out.
Investigators say a neighbor called 911 around 2 a.m., and when fire fighters arrived on the scene, flames were shooting through the roof.
The home was destroyed and the children's mother, Jackie Pham Nguyen, and a friend, were injured in the fire.
ORIGINAL STORY: Grandma and 3 children die in Sugar Land house fire, officials say
Two weeks later, Nathan says the pain of grief remains a rollercoaster for him.
He opened his home to ABC13, sharing memories, the struggle of sorrow and what's next for his children's legacy.
"My family and the community and my friends have really been there for me, and I think that's what has helped," he explained of how he is finding comfort.
And then, of course, there are pictures.
“While I may always feel like their time on Earth was cut short, I am comforted by the fact that each of you were absolutely perfect in every way.”— Shelley Childers (@shelleyabc13) March 3, 2021
Heartbreaking words from the mom of Olivia, Edison & Colette Nguyen.The siblings died Feb.17th in a house fire during power outages pic.twitter.com/UVFl1xnznn
Nathan and Jackie shared dozens of photos of their children's precious smiles, giggles and sweet snuggles through a family website.
He says those tangible images have provided solace too.
Olivia, the oldest, loved to bake, embrace her Vietnamese heritage and recently discovered chess, Nathan said.
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"I gave her some books on how to beat your dad at chess. That's the title of the book," Nathan said. "And I asked her if she's been reading it. And she said, 'Yeah, I've been reading it.' I was like, 'You're doing really good.'" He said the last game he played with her was a chess match in which she nearly beat him for the first time.
Their only son, 8-year-old Edison, loved art and recently picked up the game Dungeons and Dragons, Nathan said.
"He just loved it and would not stop talking to me about it," Nathan recalled. "I was just really happy to find something he could do with me."
And then there was little Colette. Although she was small in stature, she was the star of the show.
"She loved to entertain people," Nathan said. "She would stop us during dinner and ask everybody to be quiet so she could sing her song about cranberries and strawberries and bananas and, you know, put on a show for us."
Over the past few days, tributes to the children have filled the halls of St. Laurence Catholic Church and School in Sugar Land where the siblings were enrolled.
Early on, Nathan and Jackie established separate GoFundMe accounts with goals of creating foundations in honor of the children.
SEE ALSO: How you can help family of 3 children killed in Sugar Land house fire
Nathan says money raised from supporters around the country will be donated to the St. Laurence Catholic School tuition assistance fund and to assist the Sugar Land Fire Department with public education engagement and tools.
"We would like to donate things like fire blankets, a ladder for the second floor, because that's where the kids were, and hopefully the fire department could help another family," Nathan said.
"I know they would want me to know they're okay, because that's how good they are," Nathan said when he was asked what he thought his children might say to him today. "That they want me to be okay. They really cared about their parents."
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