One was an avid golfer who kept birds as pets.
The other had a passion for cars.
For nearly three decades, Mr Tan Kok Keng, 67, and his son, Mr Mark Tan Peng Liat, 29, lived together in their West Coast Rise home, seemingly without incident.
But on Tuesday afternoon, something went terribly wrong.
Neighbours reported hearing a woman's screams, and the police were called at 5.25pm.
They arrived at the semi-detached house at 58, West Coast Rise, and the older Mr Tan was taken to the National University Hospital (NUH) unconscious.
He was pronounced dead at 6.48pm.
A police spokesman said a 29-year-old man had been arrested in connection with the incident.
The New Paper understands he is Mr Mark Tan.
He will be charged in the State Courts today with murder.
So what went wrong?
According to Chinese evening daily Shin Min Daily News, the father and son were in an argument, which led to a scuffle.
Their Indonesian maid, who witnessed the incident, ran to the home of Mr Tan Kok Keng's sister on the next street to seek help, and the police were called.
TNP understands that when the older Mr Tan was taken to NUH, his son had accompanied him in the ambulance and was arrested later.
One neighbour who lived down the street said his maid heard shouts and screaming at about 5pm on Tuesday.
But since she was busy preparing dinner, she did not think too much about it until her employers pointed out the heavy police presence on the cul-de-sac of about a dozen houses.
Said the man, who did not want to be named: "There must have been about 30 police officers.
"They cordoned off the entire road from about 6pm till past midnight."
A woman, who wanted to be known only as Mrs Sein, who lives next to the Tans, said the family hardly spoke to her in the two decades she has lived at West Coast Rise.
"I only know the older man likes keeping birds because I see the cages hanging by the side of the house, but he never spoke to us. They were very private," she said, adding that she had never heard any arguments in the home despite living next door.
Another neighbour who declined to be named said the father and son did not seem to go out to work at regular times, and were at home a lot.
"Sometimes we'd see the older man going out, and he'd have a cap on," she said, adding that the duo would leave and return separately.
Another neighbour, who lives a few houses down, called the older Mr Tan a "generous man" who gave all the maids on the street red packets every Chinese New Year.
According to accounting records, the older man used to be involved in at least nine marine-related businesses, though the companies have since been dissolved.