He is a former convict and a secondary school dropout who has spent around two decades in and out of prison for drug offences.
She is a Hwa Chong alumna, a master's graduate who studied in the United States and now sits on the boards of directors of a dozen firms and charities.
Despite living in two different worlds, Mr Joel Lee Hong Seng, 49, and Madam Lorinne Kon, 52, are close friends who enjoy each other's company, often reminiscing over tea at a coffee shop near his flat or listening to sermons together in church.
With a recent study concluding that Singaporeans do not mix across social classes, their genuine friendship is a statistical anomaly.
The study found that Singaporeans' social circles tend to be limited to those who live in similar types of housing and have similar educational backgrounds. Those who participate in religious organisations or volunteer for social causes, however, are more likely to expand their circles across such divides.
Mr Lee now lives alone in a one-room rental flat in Jalan Besar. But for nearly seven years, his home was Cluster A2 of Changi Prison.
In stark contrast, Madam Kon, who is married with two children, lives in a 1,600 sq ft condominium unit in Balestier.
Now a delivery driver, a job he found thanks to the help of Madam Kon and other friends at Paya Lebar Methodist Church, Mr Lee says his life of crime and drugs is over - all because of a chance encounter in 2014.
Then, she was one of three Thursday volunteers with Prison Fellowship Singapore (PFS), which conducts regular weekday Bible classes for inmates. Says Mr Lee in Mandarin: "She sat next to me during the Bible classes, so when there was a passage that I couldn't understand, I would ask Lorinne."
Her first memory of Mr Lee is of him asking thoughtful questions, and of his attentiveness in these classes. He would also shush others when their attention lapsed, reminding them that the volunteers were there every week out of goodwill.
Technically, the PFS programme ends when the inmate is released. But Madam Kon continued to keep in touch with him.
Their shared religion kept them connected at first, but eventually both found another common cause: to make sure Mr Lee stays clear of harmful substances as he re-enters society.
"As soon as I came out, I have my old friends asking me to go (drink) Martell," says Mr Lee, referring to a brand of cognac.
"But for the first time, I told them no. I have other friends now. I no longer hang out with those guys."
From time to time, she would share with him information on job opportunities.
He would also call her for help in navigating bureaucracy, such as which MP to contact when his late father suffered a fall, leaving him with unpaid medical bills to clear.
Madam Kon says she arranged for him to meet his MP Denise Phua, and accompanied him to the social service office near his flat to apply for financial assistance.
The reality of being poor in Singapore was not something she had been exposed to before.
By her own admission, Madam Kon is privileged. She was chauffeured to school as a child in the 1970s, received an overseas education and has lived without fear of poverty.
"All my life, I have never been taught the value of saving for a rainy day. It was after I met him that I realised certain things that are so inconsequential to me, like spending money, mean so much to him.
"Our world views are so different, and I have learnt so much from Hong Seng," she says.