In reality, Linda was my stepmom for 3 months (that's how long she was married to my dad).
Good morning, Jesser.
It seems that Linda represents a transitory authority figure - someone whom you currently must respect, but perhaps not permanently - like a teacher, for instance. However, just as Linda's instruction seem pointless and counterproductive, so do the orders you're getting from the person in your waking life. You also seem to have different priorities - Linda wants to protect her cat from the hogs, and you want to protect the fish from the cat. So, while you have to listen to this person for now, you really don't want to and are just putting in time until they are no longer in charge of you at all.
I think I'd go with the teacher explanation on this one - and it's likely that the best course of action for you is to just go along while you have to - it is, after all, only temporary.