So, back to my acid-breathing (sulfuric acid, pH 0.2-0.1, 1-3 liters can be stored at a time) dragon.
So, the Dragon's life isn't exactly great, he's currently a slave working for a larger town, he previously raided for food (nothing really fancy, just snuck in and stole a handful of apples a few times).
Only five people consider him to be (gasp) a living and feeling creature, plus he has to risk his life on a regular basis during military campaigns.
What about peacetime then? I mean, the setting has times of peace, though ceasefire would be a better term. What would the Dragon do then? More precisely, what would they make the Dragon do then?
Doing some helpful work would theoretically be good at convincing the already extremely racist Church that the Dragon is not the reincarnation of Trash Man (this world's equivalent of Satan), or at least it's a safer attempt than the time they gave the Dragon an educational tour around fantasy Vatican, which nearly ended in bloodshed.
The world itself is your average perma-medieval world with lots of zombies walking around during night. They aren't bright or strong, but there's a lot of them.
Zombies are grown in the tubers of a very abundant plant, making them extremely numerous. Acid is effective against them, but overall, it's really not worth fighting them, as walls are enough to keep them out.
The Dragon is a hexapodal, warm-blooded creature with an extremely long lifespan. He stands squarely 2 meters at the shoulders, but is less bulky than a horse of that size, and has a vent-snout length of 5 meters. His laterally compressed tail is half the total body length (so, also five meters). You really don't want to get whipped by it.
The dragon's body is covered in red scales, which provide ample protection against swords maces and even guns, as well as against the dragon's own acid. Of course, he isn't invincible. Sufficient force, the right disease or simple tiredness can still get him.
While it seems unlikely for a creature with that dimensions to be able to fly, it's sort of manageable. Pterosaurs like the Hatzegopteryx and Quetzalcoatlus grew way beyond previously believed size limits. There are two big factors, as far as I can see, that limit a dragon's size. First is the strength of the materials that the wings and the rib cage are made out of, which we could improve without adding extra weight. Second is the food source.
Putting it together, this means that the Dragon can't use powered flight (and thus, take off) frequently. Once in the air, he can use thermals to gain altitude and travel long distances without expending energy. Flight speed is 16.3 - 24.9 m/s. Terrestrial capabilities are good, but overall strength obviously suffers because of the high mass fraction of the flight muscles.
As far as senses go, the Dragon has a good (dog levels of good) sense of smell, complete with a Jacobson's Organ. Hearing is decent, eyesight is very good, on pair with golden eagles. He possesses nictitating membranes and is able to seal his nose (like otters) and hold breath for a while (thanks to the abundance of air sacs).
"Wow, this dragon seems pretty OP, how could they even make him a slave?", you might be asking. The answer is one half death threats, in the form of the aforementioned disease and "dragon-slaying" weapons, contaminated with it.
The second half is magic, namely, very rare compulsion spell that makes the Dragon carry out the orders of his superiors in an unconscious/sleepwalking state, if he doesn't do it out of his "free will". Note that the spell activates only when he's defying direct orders.
For conflicting orders, the one issued by the higher authority figure takes precedence and feasibility takes precedence over authority, if the order is impossible to carry out.
In practice, if he's tasked with bringing "Piggy" (how he calls
Robert Baratheon the king) his breastplate stretcher, he can curse like a sailor on the way, as long as he's making progress towards retrieving the item. Having to go (fly) to the nearest bathroom is considered backwards progress, so it causes the spell to activate, but only when the Dragon used up all his "potty tickets" a set number of times he can go to the bathroom, though the spell can still trigger there, if he isn't making progress towards... relieving himself.
Given this information, what non-violent, civil job would be the most suitable (i.e: take the most advantage of the unique perks) for the Dragon?
The job should be one that a dragon can do in a different and miles better way, compared to humans, and is of the most use for the community.