Yip Kie-chun has spent months at a time, day and night, trawling the streets of Hong Kong searching for his mentally disabled son, only to see him run away yet again after he had found him.
Now aged 79, the retired fish hawker never gave up on his son, Yip Chi-wo, since the first time he went missing from their home in To Kwa Wan at the age of 17. Chi-wo is now 49, but he is described as having the mental age of a six-year-old.
Yip and his wife took turns manning their fish stall while the other went out to search for their son, not knowing it was the start of a pattern that would be repeated more than a dozen times in the years to come.
"We thought he was dead. He was gone for almost five months," Yip said.
It was only when Chi-wo was hit by a car and broke his leg that the family was reunited - when the hospital treating him discovered he was a missing person.
Chi-wo was then enrolled in a training centre during the day. In his two years there, he ran away more than 10 times. He often lost his temper, and Yip believed the staff lacked the experience to handle his son.
Each time, Yip would take to the streets to look for Chi-wo.
"At the end of the day, he's our son. You've got no choice. Why would I not love him?" he said. "Sometimes we would find him wandering in the streets, looking very thin. Bus drivers gave him food and he slept in trucks."
Next for Chi-wo was Castle Peak Hospital, a psychiatric hospital in Tuen Mun, from which he also ran away several times.
In 1990, he was seen peeing in the street by a teacher, who reported him to police. Yip says his son's hand was gripped round a pen by officers when he wrote the single word "understand" on the police statement. Psychiatrists then assessed him as fit to plea in court.
Chi-wo admitted indecency in public, and the court gave him a conditional discharge for a year.
The fish hawker has learned a lot about the discrimination and lack of knowledge surrounding people with mental disabilities.
For the last two decades, his son has been in a care home, where his father says he is given love and respect - and plenty of music CDs, which are his passion. His behavioural problems have lessened over time he has lived there. More importantly, he has not run away again.
"He knows what he is doing," Yip says with a certain pride. "You have to give him freedom instead of taking control over him all the time."
Chi-wo returns home to his parents at weekends.
"He behaves well when we take him out. He walks ahead, but looks back and waits for us," Yip said. Forget the cards and aftershave; that backward glance from his son is one of the greatest gifts Yip can hope for on Father's Day today.
Somehow the father-son bond seems even stronger when Yip adds: "We don't hold hands; he doesn't like holding hands."