On the last day of his life, the toddler had been with his grandmother, who was supposed to take him to daycare. But after picking him up from his parents' home in Milton, Ont., there was a tragic moment of confusion where she believed she had dropped him off.
His grandmother had worked the night before and ended up going to sleep. And she would end up driving back to the daycare to pick him up later that day, shortly before she would learn he was still in the car.
Maximus was just a few weeks shy of his second birthday at the time of his death.
His mother, Tamara Huyskens told CBC News today that losing her young son a year ago has been "absolutely life-changing" for herself and the surviving members of her family.
"You never really recover and go back to the way you originally once were," she said in an interview on Sunday. "There's a huge element of our family missing, but we've grown a lot within the past year, we feel like we're a lot stronger."
For Maximus's sister, who will soon turn six, it has been hard to understand the full depth of the tragedy.
"It's just an ongoing process of going through the challenges, the milestones — they're always hard," Tamara Huyskens said. "And we just try to focus on what's important to us."
On Sunday, a fair was held in honour of Maximus. It was first held last year after the boy's death and has continued this year.
"We wanted to support the family and be there for them," said Rose Passarelli, who helped organize the event both last year and this time around.
A decision has been made to hold the event annually in a bid "to educate families, educate parents and caregivers of young children about car safety and [the issues of] children in and around cars in general."
The tragedy struck a nerve with Passarelli, who has a daughter the same age as Maximus.
"I thought that it could happen to me, too," she said.