Marvin (nolastnameknown) is the proprietor of the Ironbark Inn. He insists on continuing to relate to Rosie as Grandmother Night, despite her protestations.
Rosie later summarized this encounter in her notebook only as 'disappointing'.
Comes in at the end if s2.2 to ask Rosie for permission to serve cornerstones at the Ironbark. He knew that he was in trouble and tried to hide from Rosie after she found out that he had already made the cornerstones before asking for permission, using a recipe he stole from Propha. K'Thriss applied to help him serve but used his TENTACULAR SPECTACULAR to terrify patrons out of the inn. Marvin then agreed to donate all proceeds from sale of the cornerstones to the Lighthouse (Treehouse). Y'see? He's a good guy.