Marc is mostly active in alternate flag-making and the creation of other various alternate state insignia.
He and Ben (aka False Dmitri) had a history of contributing greatly to the Ill Bethisad worldbuilding project before joining AH.com. At times, they reference this, and point to their older interesting creations within said project.
Marc created a lot of fictional histories and supplemental material for various parts of the project, notably the nation of New Francy and the alternate sport of hibercrosse (an ice hockey and lacrosse hybrid of sorts).
A list of timelines he created at the Alternate History Wikia can be found here.
In AH.com Enterprise, the eponymous character of Marc Pasquin is the enigmatic Head Graphicsmage of The Guild of Vexilologists and Iconographers, as well as a crew member of the Guild mothership Texture. He often serves as one of the Paint Pontif's closest and most trusted advisors.