Yeah, only a rare caste of creature is going to have the ability so that might work. This interaction would definitely force the enemy entity to use the interaction on a valid target though?
The reason I want this interaction is that I'm trying to work in shapeshifting creatures (demony-type guys) who count as entity members, but flavor-wise not the same species, who usually or frequently take the form of the entity for ease of interaction. Both forms would either be different castes of the race (forcing them to be of similar size to my race so everyone could still wear socks) or the regular form would be the "human" form and it would temporarily take a different creature form. I do want to allow cross-breeding. I plan on most of them having advantages and also some major drawback that has to be managed. A sloth-demon inspired creature, besides being incredibly lazy, might give a drowsiness syndrome when you look at him (mechanically probably a gas he gives off), for example.
Of course, I haven't done any of this yet because I'm still working on fleshing out the entity's equipment, custom materials, and plants right now. The specifics of how this could be implemented are still a work-in-progress. Obviously if you got that creature at embark you'd have a problem.
Another angle I've thought of trying is just having the demon frequently take the entity form as a friendly GREETING reaction, but the wiki page I read wasn't very clear on what a greeting reaction does, exactly. Is it actually a social-inspired interaction or will he just spam it on friendlies during a fight?
EDIT: Came across another issue with my new weapon system. My entity has a unique building it uses to "craft" weapons at and that's all well and good, but I can't figure out how to give them things made of this material on embark or at least how to remove things made of other metals. They currently have no metalsmithing abilities so on embark they pick a completely random metal for their digging item to be made of. If you remove it from the Prepare Carefully list you can't re-add it since they don't actually have that metal.
Is there a way to give the entity this material (changing its material template included) so that they'll use it and have it on embark without having to give them metalsmithing?