Thomas Marvel is a tramp who becomes the unwilling accomplice of the evil Griffin. Though possessed with remarkable powers, Griffin needs someone to help him carry out his wicked plans for world domination and mass murder. Griffin first stumbles across Marvel on a remote country lane. He appears to have all the qualities Griffin seeks in a sidekick: gullibility, suggestibility, and not much in the way of intellectual curiosity.
But what Marvel lacks in intellect he more than makes up for in street smarts. (With Griffin it's almost the other way round.) He may have a seemingly chronic aversion to hard work, but he understands the value of money, and being Griffin's sidekick does allow him to lay his hands on lots of lovely green stuff. Thanks to his association with Griffin, Marvel's able to rise up in the world, using his ill-gotten gains to buy himself an inn. (Called "The Invisible Man," no less.) Marvel's bizarre little adventure with the Invisible Man has been truly transformative for his character, turning him from an ignorant, work-shy layabout into a pillar of the local community.