The story of Rupert Marais, the swimmer, remains untold. His brother Charles Marais also played water polo for Western Province, winning the Currie Cup in 1901.
He was born in 1880 and died on 1 August 1924, in Pretoria. He married Stella Felicia Emmett in St Peter's Church in Vryheid, Natal on 5 October 1905. Stella passed away in Pretoria on 11 November 196. Her sister Venetia married Charles Marais, the older brother of Rupert Marais, She was 20 years old when she married 26-year-old Charles Marais in Vryheid on 5 October 1893. She also lived in Pretoria until she passed in 1954.
In June 1901, he passed the Law Certificate Examination at the University of Cape Town. He practised as an attorney and later an advocate in Pretoria. Rupert Marais was joined by Norman Price (later to become Judge N. C. B. Price) and Charles William Clark, and the firm became known as Marais Price and Clark. Both Rupert and Norman Price were on the Board of Directors of the Standard Motor Company of Africa, where Rupert was the Chairman.