Mayall is someone who lives in the North. According to Silver, he "always seems to have a bottle of wine near him. He dissapears whenever the Kingsmen are around but frequently sleeps on the streets, even on the coldest evenings."
Mayall was later in "Renegade", and told the location of the Cotton and Blackthorn families, who were in hiding. Imp Cotton was the one who told him the location, and Silver later went to Martindale and found Mayall. He told her the location and she was reunited with her family.