This goes so much inline with my own MB class "Rat King" that could be even a pre event for his creation and backstory. <3
Viewing post in Rat Cellar | A Mörk Borg Pamphlet comments
Yeah, the characters who choose to become rats will definitely need a new class ;) For those interested, here's a link to Nicholas's class: https://nicholas2884.itch.io/rat-king-mork-borg-class
Also, this by Karl Druid could work:
https://makedatanotlore.itch.io/ratfaced-sewer-sneak