if a homestuck and a non-homestuck have a baby that baby is a homestuck because the homestuck gene is dominant and the non-homestuck gene is recessive
If the offspring has both a recessive and dominant trait, they will be a homestuck and if that offspring has a baby with another homestuck with a recessive and dominant trait, these are the possible outcomes
one note about the homestuck gene: while op is right about it being dominant, it is incompletely so. thus while an Hh child will still always be a homestuck, the recessive h gene will affect some smaller details of their homestuck-related views (eg. their opinion on vriska)