Without magic or Psionics (aka mind magic)? You can't, not unless you don't mind them simply not being completely inside.
I'm assuming by the examples you gave that by "authority" you mean the parasite can control what the victim does either fully or up to an extent. Problem is that, by default considering earth's biology, a parasite needs access to what the victim has inside of it, and that is true for every single parasite species on earth. You want to control that ant's brain and have it climb to the prefect place to release your spores? Find your way inside it. You want access to that animal's sweet post-digested nutrient goodness inside its intestines? Find your way inside it. You want blood inside their veins? Find a way inside them (because technically making a cut through the veins to get the blood is still a way to get access to their internal portion, even if that includes breaching them). You want to becomes that fish's tongue and live inside its mouth feeding on nutrients provided by its bloodstream? You guessed it. Find your way in and get that tongue out.
And that is the problem about your context: the closest potential thing you could use within the bounds of earth biology are, well, pheromones, but that would rely on the creature understanding said pheromones to begin with (also, yes, ants communicate through pheromones, but pheromones don't really work as some kind of chemical control panel where each pheromone dictates and action. Creatures like ants use them to share information, but instinct plays an important role into determining who does what and when depending on the information relayed by the pheromones).
Your best bet for some kind of control over a victim with zero physical interaction would be magic or some kind of powerful Telepathy, both of which aren't exactly based on reality.
So essentially, that leaves us with the last best option: if you can't reach their brains and nervous system through mind powers or magic, reach it through a needle.
Essentially, the creature latches onto the back of your neck, sticks a needle into your brain through the critical opening in your skull meant for the spinal cord to have somewhere to access it, take control over both hypophysis and other parts of the brain and its set. You don't even need to take control over the full brain, all you need is for it to twist it just enough to make you no longer see the thing attached to you as something harmful or which shouldn't be there. After that, linking itself to the nervous system, it will interpret what the body needs and take over what both hyphophysis, the hippocampus and other portions of the brain do, particularly regarding hormone production.
Why hormones? Because they're already produced by you by your own body, dictate a good portion of how you function and how you feel, and if you ever gain immunity to them, there's a chance that you'll die without some sort of medical assistance (diabetes type 2 for example is what happens when your body becomes resistant to insulin). You want the thing to do something? Teach it. Release reward hormones that make it feel good when it obeys the voice in its head and make it feel like garbage when it doesn't. With enough training, you hopefully get something that does as the voice says unconditionally.
In such a relationship, the thing cannot be considered as a mutualistic organism, the thing it's attached to could live just fine, if not better off, without it. Yes, it's not completely outside of the victim and it technically is relying on chemicals, but at the same time, no creature can develop a resistance to it, because it's parasitism relies on it having a brain with openings through which it can link to the spinal cord and using hormones, both things it cannot avoid and will likely die in case it does.