aka "Rat Man"
Merek Forman is an underhanded dealer and thief who works in the slums of Sigurdsholm.
Forman did some work for Steel-Eyed Susan’s gang, and was nominally part of the Black Masks. After learning the truth about her revival, he tried to get out, but Halde cursed him to take the shape of a freakish rat/man hybrid. Forman retreated to the sewers, and used his newfound ability to communicate with rats to send for help.
While cursed, Forman clashed with a student from Seidhrskjold Wizards’ College, who ended up dead. He asked Fulkhard to help him dispose of the student’s belongings, and ordered his rats to devour the body. To his knowledge, all evidence of the encounter has been destroyed.
Taavi Firuz, Fionn Mac Tire, Immeral, Damakos, and Anastasirra eventually answered his call, and Forman hired them to remove the curse. The party captured Halde and forced her to break the curse, then wiped out the Black Masks.
Forman has since resumed his unsavory everyday life, although he can still communicate with rats, and makes use of the sewers for quick travel through the city. He also introduced the party to Fulkhard, with whom he occasionally dinners.
Image source: Wizards of the Coast.