They are children of super-rich parents - President Robert and Grace Mugabe - who are broadly disliked in Harare, their hometown.
Most people in the capital support the opposition Movement for Democratic Change (MDC).
The Mugabe boys grew up protected from the public in many ways and were always surrounded by security.
The births of Robert jr and older sister Bona - born when their father was married to his first wife, Sally - were kept secret until Bona started school.
Bellarmine Chatunga was born after Robert and his second wife, Grace, married after Sally Mugabe's death. Sally had been hurt by her husband’s infidelity with Grace, according to friends in the ruling Zanu-PF.
Sally and Robert Mugabe’s young son died of malaria in Ghana when Robert was in detention in the former Rhodesia.
The Mugabe sons were also isolated because they were always out and about with security and grew up in Zimbabwe’s never-ending financial and political crisis. And their parents have few visitors, few friends.
Harare is a dull town. There isn’t much night life or diversions, and although they followed football and went to official events with their parents, and had all the gadgets, they didn’t have much fun with children of their own age.
As with most children of Zimbabwe’s political elite, they studied in South Africa or abroad as Zimbabwe’s shabby tertiary institutions lack facilities and do not have a good academic reputation in most disciplines.
They are, after all, sons of the only leader Zimbabwe has known. Zimbabweans are frightened of him and are increasingly poor, short of foreign currency for imports and 90% of the population have no jobs.
But the Mugabe sons are proud of their parents as they say on their Facebook pages.
People who have spent time in the Mugabe’s massive private family home in the Borrowdale suburb say that he explains to his family that all of Zimbabwe’s problems are caused by the West or droughts.
Neither of the Mugabe boys performed well academically and Robert jr was given a tough time by other pupils in the rural Catholic school his father attended about seven decades ago.
A former Zanu-PF insider, who remains loyal to the president, said at the time that Robert jr, or "Tino", left this school because he was bullied for being Mugabe’s son. He was sent to a superb private school in Harare, St John’s, for his A levels.
One teacher who had some contact with him at the time said he was polite, modest and tried not to be noticed. Robert jr ensured his security guards kept a low profile. He wanted to be a regular boy.
Although he failed all his examinations and this was admitted by his father, in public, he became a superb basketball player. Grace implied that US "sanctions" prevented him from furthering his sports career in the US. But the children were not prohibited from travelling there.
The younger Chatunga Bellarmine had a similar upbringing, but he was sent to Catholic schools in Harare from the beginning. He didn’t do well either. But he was not polite and modest like his older brother, and was expelled from St George’s when he was 16, for bad behaviour.
It is not clear whether his subsequent home schooling produced any results.
On Facebook, he has hordes of friends and displays many pictures of himself wearing top-of-the-range clothes in Sandton Square, for example.
Chatunga is thought to be more outgoing then Robert jr. He always has a great deal of money on him, according to close observers.
The Mugabe sons arrived in Joburg early this year after a hurried departure from Dubai where they had lived in a R500000 per month mansion.
Mugabe chartered an Air Zimbabwe Boeing 767 and rushed to Dubai to pick up his sons so they could leave the United Arab Emirates without incident.
The Mugabes have not denied that their hastened departure was connected to alcohol or drugs.
Since leaving Dubai, Robert jr is reported to be studying design at the University of Johannesburg, while it is unclear if Chatunga is studying. He seems to have a couple of money-making schemes on top of the money that is sent to him by the first family.
He is said to always have the readies for expensive imported booze on the brothers' frequent visits to the posh Taboo nightclub in Sandton.
The Zimbabwe Independent reported last month that the brothers were kicked out of their R70 000 per month apartment after a drunken brawl.
Grace had to rush to Joburg to discipline them and get the flat fixed.
They were then supposed to be living in her huge rented property in Sandhurst, which is well guarded by Zimbabweans.
Without their mother’s knowledge, apparently, they had rented two flats within a Sandton hotel for about R60 000.
It was here that Grace Mugabe arrived last Sunday and allegedly attacked 20-year-old model Gabriella Engels, who had met Chatunga only the day before at the Taboo nightclub.
She worked there three times a week as a hostess and hopes to return to her job when she has recovered her confidence and after her head wounds have healed. Unlike the Mugabe sons, she has never had money to study.
The sons were still in Joburg on Friday, and it is not clear whether they will continue with their lives in South Africa or return to quiet, dull Harare.
Independent Foreign Service