Mather was an egoistical individual. He strongly advocated for the Knights to take a more proactive role in Waterdeep's businesses but was soon in fear that his bosses would discover his role in the demise of Nindil Jalbuck.
Mather was a merchant and occasional slaver from Tethyr and often in Waterdeep for business. Once, he stayed at the Yawning Portal with a pair of slaves, thus earning the ire of Durnan. From that time on, Mather adopted a low profile in his visits to the city.
For a long time, he tried to convince fellow Knights to put one of their own among the Lords of Waterdeep. Finally, First Shield Lord Inselm Hhune told him the name of a probable Lord: Nindil Jalbuck. However, Bly Ruldegost, Mather's immediate superior in Waterdeep, forbade him to act against Nindil. So Mather sold the Lord's name to the Unseen for money. Afterward, he was terrified that Bly or Hlune would discover his treasonous act.