When two symmetric Agents are collected in a single NP functioning as a set, it is marked as a Whole construal:
Many event predicates license multiple participants acting in complementary ways and portrayed as having independent agency. In such cases, an Agent scene role is allowed for either participant, even if one (typically realized in a syntactically more prominent position, such as subject) is perhaps understood as slightly more agentive:
In other cases, a second "extra" participant may be portrayed as accompanying the first in the event—possibly acting volitionally, and possibly implying some sort of additional social interaction or alignment of goals, but not strictly necessary for that kind of event to take place. Together_with serves as a diagnostic for these participants, which are labeled simply Ancillary.
Animate (and typically volitional) participant instigating an action or acting in a complementary way to the instigator.