During the Great Council of 136 AC, three regents were selected by lot to serve in the regency for King Aegon III Targaryen. Lord Lorent Grandison was among the three regents selected, considered an inoffensive, though undistinguished, choice.
When Lady Cassandra Baratheon was found guilty of conspiring to poison Queen Daenaera Velaryon, three bannermen of House Baratheon spoke for Storm's End at the trial. Through them and Lord Grandison, Lady Cassandra was arranged to marry Ser Walter Brownhill, a minor landed knight. While the regents and Lord Torrhen Manderly, the Hand of the King, were discussing King Aegon III's first royal progress, the young king entered the room and dismissed them all, for he had come of age.