Ferocity is taken into account ONLY if the Obscene is directly attacked.
Right, because that's the only way it can Counter. It's the same situation as with the Riverwatch Riders. Obscenes can't use Ferocity against Riders before they retreat because Riders can't be Countered. Same thing here. If they can't Counter in the first place because they weren't attacked, they can't use Ferocity.