Patrick became a prominent figure at Court, and served as a "sewer" (assistant) to the King at the baptism of his son Prince Henry Frederick in 1594. He ruled Orkney and Shetland in the north of Scotland in the manner of an independent sovereign, severely oppressing the islanders and getting into massive debt. In 1599 he built Scalloway Castle on the Mainland of Shetland, partly to strengthen his power there against his half-uncle Laurence Bruce, who had been appointed Sheriff of Shetland by the deceased Earl Robert. Patrick also feuded with George Sinclair, the Earl of nearby Caithness. In March 1599, James VI ordered Patrick and George to furnish their strongholds against the possibility of an invasion by the exiled Earl of Bothwell. This scare was renewed in July 1601. In 1607 Earl Patrick began the construction of the Earl's Palace in Kirkwall, the capital of Orkney.