Silas was a rebel soldier during the Orlesian occupation of Ferelden. Years later, he was hunting on the grounds of Arl Urien of Denerim without permission when Harwen Raleigh captured him and locked him in the dungeons of the Arl's estate. He was there for some months when Leliana finally found him.
This section contains spoilers for: Leliana's Song.
He is found in the dungeon by Leliana after she is betrayed by Marjolaine. After he escapes from the dungeons he joins Leliana and Sketch, in their pursuit of Marjolaine and Raleigh. Once Raleigh and the soldiers of his mercenary company, 'The Hard Line', have been defeated at Forlorn Cove, Leliana may choose to let Silas kill Harwen as repayment for his suffering at Raleigh's hands. Afterwards Silas becomes a member of the chantry. He may use Tug's Edge as a weapon if it is given to him as a gift by Leliana.