Tobias Homlomium

Professor "Tobber" Homlomium (real first name unknown) was a spark, a member of the Queen's Society, and a researcher on multidimensional space, with particular interest in possibility that higher dimensions are by powerful beings who might object to the manipulation of time, specifically at Mechanicsburg. So he derives purely from theory something the reader (along with Gil and Higgs) has been shown by the Castle.

This result apparently makes him too dangerous, to someone, to be allowed to meet Agatha. Thus he is murdered; a backup of the plumbing in his lab turns out to be caused by his clogging the drain.