Timothy Archibald began photographing his son Elijah at age 5, before the boy was diagnosed with autism. It started as a way to document Elijah's behavior that Archibald just couldn't figure out, but ultimately brought the pair closer together.
"The mystery was the fuel," Archibald, a photographer based in San Francisco, told ABCNews.com. "It was a father-son project we were jazzed about. He was posing in photos and would run around the back of the camera and say, 'That's it. We got it.'"
The photo project is called Echolalia, a word used to describe a behavior common in autistic children in which they repeat words or phrases. Archibald said the photos paint a picture of autism in a way that words can't.
Elijah, Archibald's oldest child, was born in 2001, but it wasn't clear something was different about him until the Archibalds' second child was born. By the time Elijah got to kindergarten his differences became "all encompassing."
"Everyone wanted to know what was up with Eli," Archibald said. "It took over the home, it took over everyday life. I started to photograph him almost as data collection."
Although bloggers have come across the photos and written about them time and time again since they were first published in 2010, Archibald said the attitude toward them has shifted.
"In 2010, people didn't love this project," he said. "It made them uncomfortable more than it seemed to touch them."
Back then, about 60 percent of the commenters would accuse Archibald of exploiting his son and the other 40 percent would defend the photos, he said.
So when Archibald saw a blogger call the photos "heartwarming" a few weeks ago, he was floored.
"When the project originally came out, no one would ever call it that at all," he said.
Elijah, now 12, travels with his father on occasion to talk about the photo project, and he loves it. Last year, on a trip to Atlanta, an audience member bluntly asked Elijah what it "feels like" to be autistic.
"He said, 'I don't think I could tell you what it feels like to be autistic. To me, it feels normal. This is all I know.'" Archibald recounted. "'This is normal.'"