Shakuni’s story is probably one of the most interesting and yet less famous of all of Mahabharat’s sub-plots.
Gandhari’s horoscope showed that her first husband would die and leave her a widow. To avert this, on an astrologer’s advice, Gandhari’s family married her to a goat and then killed the goat to fulfil the destiny and assumed that she could now go ahead and marry a human and since the person technically be her second husband, no harm will come to him.
When Dhritrashtra’s proposal came for Gandhari, Shakuni was never happy about his sister’s Gandhari’s marriage to the blind Dhritrashtra – more so because Dhritrashtra had been overlooked and the kingdom had passed to his able-bodied brother Pandu. He made his dissent known but was not heeded and Gandhari was married to Dhritrashtra.
However, the secret about Gandhari’s first marriage to the goat came out and this made both Dhritrashtra and Pandu angry at Gandhari’s family – because they did not tell them that Gandhari was technically a widow. To avenge this, Dhritrashtra and Pandu imprisoned all males of Gandhari’s family – including her father and her 100 brothers. Dharma did not allow killing prisoners of war, so Dhritrashtra decided to starve them slowly to death and would give only 1 fistful of rice for the entire clan everyday. Gandhari’s family soon realised that they all will starve to death slowly. So they decided that the entire fistful of rice will be used to keep the youngest brother, Shakuni, alive so that he can take revenge on Dhritrashtra later. In front of Shakuni’s eyes, his entire male family, starved to death and kept him alive. His father, during his last days, told him to take the bones from the dead body and make a pair of dice which would always obey him. This dice would later be instrumental in Shakuni’s revenge plan.
After the death of the rest of relatives, Shakuni did as he was told and created a dice that contained his father’s bones’ ashes. Then he talked his way out of prison, became close to Duryodhana and started on his evil plan of revenge which included the destruction of Dhritrashtra’s 100 sons to avenge the death of his 100 relatives. The rest, you all know.