Before The Sorcerer in the North starts, Sir Keren had been slowly poisoning Syron, using a poison that gave the same symptoms as the poison from an old legend. Most of the people presumed that Lord Orman had poisoned his father, as Sir Keren was popular whereas Orman wasn't, being more of a scholar than a warrior or Lord.
He dies from the poisoning during The Siege of Macindaw, imprisoned in his own castle.
Lord Syron was said to be a good man, implying that he had a good personality. It is assumed though, that he has a certain amount of steel in him, as he was Lord of Macindaw, a place with high importance due to the Scotti in the north.
Syron might have not had much trust in Sir Keren, as he refused to award Keren for his services, causing the latter to poison Syron. It is unknown what was his standing with Orman, but when his death was told to Orman, the latter was greatly saddened, hinting a good father-son relationship.