Short answers, pulled from the story.
Rafi ud-Darajat was the eleventh Mughal emperor, placed on the throne in 1719 by the Sayyid brothers after they deposed and executed emperor Farrukhsiyar. He was the youngest son of Rafi-ush-Shan and a grandson of Bahadur Shah I, chosen to serve as a puppet ruler under the brothers' control.
Rafi ud-Darajat reigned for three months and six days, from early 1719 until his death on the 6th of June 1719. He was born on the 1st of December 1699 and died at age nineteen.
Rafi ud-Darajat granted Chauth and Sardeshmukhi rights across six Mughal provinces to the Marathas. These revenues were to be collected by Mughal officials and then handed over to the Marathas.
The Sayyid brothers were Sayyid Hassan Ali Khan Barha and Sayyid Hussain Ali Khan Barha. They deposed emperor Farrukhsiyar with help from Ajit Singh of Marwar and Balaji Vishwanath, placed Rafi ud-Darajat on the throne, and effectively ruled the empire as kingmakers throughout his brief reign.
Rafi ud-Darajat died on the 6th of June 1719, but the exact cause remains uncertain. Sources suggest either tuberculosis or murder. He was nineteen years old at the time of his death.
Rafi ud-Darajat was succeeded by his older brother Rafi ud-Daulah, who took the throne as emperor Shah Jahan II two days after his death. Rafi ud-Darajat had personally requested this succession before dying.