Hiranyakashipu Holika, the sister of Hiranyakashipu was the one that sat on fire with a boy named Prahlad. Hiranyakashipu had intentions to kill Prahlad because he declared that everyone worshipped only him as God but his son called Prahlad did not obey his father as he refused to worship his father. Hiranyakashipu was upset about this and he wanted to kill his son.
So Hiranyakashipu asked Prahlad to sit on his sister’s lap on a burning pyre. Meanwhile, Holika had a special garment that prevented her from being burnt by fire. While this happened, Prahlada chanted in Vishnu's name and the special garment left Holika and covered Prahlad and Holika was harmed by the fire but Prahlad was not harmed by the fire.
It was King Banjan, who had a sister named Holika. Holika is actually a demoness who has the ability to play with fire. The main goal of King Banjan is to make Prahlad sit on Holika’s lap so that he will get burned. Holika will not be consumed by flames because she has a special cloak garment that will provide her the protection she needs.
Those who know the story are aware of all the evil that the King can provide, but even so, the story also shows that even with deceit, evil will not triumph over good. There is a celebration for this event in the Hindu tradition.