Detail #12: Entirely unmarked comitatives

In a language that marks the person and number of the subject on the verb, as well as having an accusative case, it would be cool to mark comitatives this way: nominative nouns that never trigger subject agreement (note: the nominative in such a language would basically just be used for subjects, complements and this kind of unmarked comitative). The comitative nominative is likely to be dislocated from the subject:

I.nom go.1sg fishing brother.nom

I go fishing with my brother

However, this is not used for comitatives semantically associated with the object; if the language also had object agreement on its verb, a similar object that does not trigger object agreement could be a neat 'parallelism'?