Lord Sheffield is a middle-aged, gentle man with a deep sense of personal honor and propriety which is shared by his wife. The couple have a daughter, Selana, and at least two sons; Jason Sheffield is his heir-in-waiting. His estate lies in Havesly, a large moated compound decorated with family portraits, stained-glass windows, and a library upstairs. Guards were always posted before his estate, as befitted the station of his House. He kept Calvert Bryce as his House mage, and welcomed Gregor the joyman into his household during the latter's visits to Havesly.
In the past, Lord Sheffield helped the abused wife of a Chailan nobleman flee the country, seeing that she was hidden until her husband stopped looking for her, despite his ability to interfere in Sheffield's supply lines and contacts. The woman still lives in Havesly, and praises Sheffield as "a good man, a man of great honor."
Lord Sheffield's finances, managed personally at the Mantigua Holding Company, a bank in Havesly, are deeply tied to the salt trade. The recent shipping strike and pirate activity on Antara's coast, occurring alongside Wraith attacks on his trappers in the Ridgewood, have severely depressed merchant activity, and many, including the salt-miner's guildmaster, have moved their business to Ticor, lured by Lord Caverton's financial inducements.
Together with Lord Nathan Escobar, Lord Sheffield arranged a marriage between his daughter Selana and William Escobar. William visited Havesly to meet Selana, sailing home on the ill-fated Fair Current, which is lost in a joint attack between pirates and a griffin as the game begins. William and Sheffield next meet in Ticoro, to which the Sheffields have traveled for the Festival. Despite Caverton's interference making the trip more business than pleasure for Lord Sheffield, he asserts that his position is secure and enjoys hearing about his wife and daughter's festival activities, wishing them time for frivolous enjoyment. He asks William to visit Selana at an inn in the northeast of town and tells him not to be a stranger.
This article contains plot or ending spoilers.
When visited by William in Havesly, Sheffield declares horror at the recent attack on the Imperial Family, stating that losing the Emperor at a time like this would throw Antara into chaos. He denies involvement with the pirates, noting that his own ships have not debarked since the start of the shipping strike, and expresses disbelief at the party's news that Gregor was an agent of Lord Caverton. When told of the griffin that took Gregor's life, Sheffield guesses from its intelligent behavior that it was a magical hybrid between an Ethereal creature and one of Ramar.
Unbeknownst to Sheffield, somebody has opened a messenger-tended account in his name, filling it with proceeds from an illicit agreement -- also in his name -- to allow pirates to take refuge in his private coves. When the pirates receive a message revoking the agreement, they attack his estate through a cellar tunnel which leads out to the coast. Attempting to defend his family, Sheffield slays a man who had been pursuing his daughter through the tunnel and is discovered there by William, who has found evidence linking Selana to the both the pirate activity and the Shepherds' kidnapping of the Imperial Consort, and Bryce to the Wraith attack in Antara. At first disbelieving, Sheffield asked whether anyone in the household wasn't involved in the plotting, and grieved that Selana had not behaved as befitted their House. Selana protested that she had been trying to save their House from ruin, and that if she had come to him, he would have dismissed her as a frivolous girl to be trotted out on state occasions and married off to the House's financial benefit. But though Selana had aligned with the Shepherds, believing despite their advocating genocide of the Grrrlf that the civil unrest they sowed could be used in her family's favor and that the Consort could be safely ransomed back to Chail (a time-honored practice there), and though she would not have minded William's death with the Fair Current though the pirate attack had been aimed at Gregor, she had not been in league with Bryce, and had revoked their privileges in Sheffield's coves after news about their depredations. After these revelations, Lord Sheffield remains behind as the party leaves to search for Bryce, wishing to speak with his daughter in private.
Despite this precaution, Bryce gets to them first and transports them to the Waste as his captives. After his death and the discovery that a Wraith still holds the missing souls of the Daughter-Heir and the Consort, Lord Sheffield and Selana help Aren Cordelaine compel the creature to emerge from Etherea into Bryce's workshop. The Wraith refuses to release the souls, which it intends to feed its hatching offspring, without an equal number of souls in return. Lord Sheffield, to redeem his family's honor, offers his soul willingly, telling Selana that her mother will understand; his grieving daughter does the same. William assures the two that the Emperor will know only that they sacrificed their lives for the good of the Empire. Kaelyn hands them doses of poison, laced with mint "to take the bite off," and they willingly trade their souls for those held by the Wraith, saving the lives of the Daughter-Heir and her groom-to-be.
After their death, Lord Jason Sheffield takes on the governorship of Januli, and does well despite his late sister's doubts.