The Master Writer of the Order of the Writers of Ages. The Sirdar is a Time Lord who possesses unlimited temporal-perception, which surpasses that of all other Time Lords. He not only sees all the possibilities of time, but all the concrete events of time that will happen in every reality and he continually records them.
He was taken out of all known realities by the Esse to an unmapped plane of existence called The Expanse. There he fashioned The Core, a repository of all history, from his tardis, wrote the Rule of the Writers and established the Order, starting the process of selecting potential writers for the Order by scanning all of time for the detection of Kronixus, the Time Strain particle in the brains of just one in three billion humanoid life-forms across time and space. Contrary to any moral considerations, he removes them from any point in time and writes them out of their personal timelines to become Writers of the Order, called Chronicles.
In addition to unlimited temporal-perception, the Sirdar has the power to write events of his own desire into being, and is able to grant this ability in limited amount to all the Chronicles by the use of the Chamber of Existence, but this practice is forbidden in the Rule except under dire circumstances.
The Sirdar has written the history of the Time Lords and much to his exasperation is intimately familiar with the Doctor’s exploits around the universe, resulting in multiple re-writes of temporal history.