This story is from way back in the ancient days of D&D. Our small band of four players consisted of a Fighter, a Ranger, my Cleric and the DM's NPC Wizard. We started at level 1 as we usually did back in the day and my growth from humble Necromancer to powerful ruler began right around level 2.
Our small band had been tasked to investigate a village out in the frontier of the empire. All communication had been lost and the scouts sent to investigate hadn't returned. We spent a week riding there and discovered that the entire village had been enthralled by some evil force. Even though the enemies were simple townspeople, we didn't want to kill them and their far out-numbered us so instead of fighting we snuck around the village, trying to find the source of the spell. Eventually, we determined that a statue in the village square was cursed. We destroyed the statue after fighting our way through the manic cult followers that had made the statue and the villagers snapped out of the spell. We were hailed as heroes and returned to the noble's castle to receive our reward.
What the party didn't know is that my 'Cleric' was actually a Necromancer with a whale of a backstory that the DM had agreed to for the sake of the plot. Where most Necromancers were evil, mine simply wanted to help people and delve into ancient cultures and ruins. I had all the usual Healing spells because I studied both sides of death, the living as well as the dead, but I could also animate the dead starting at level 2.
Something else that the party failed to find out was that I'd recovered a fragment of the statue. The evil spirit that the cultists had trapped inside spoke to me in my mind, trying to get me to do evil deeds in exchange for more power. I always managed to avoid the evil deeds thanks to a lucky series of Saves but I got the power anyway. Each night, while on guard duty alone, I would animate one Undead minion and send them toward a distant ruin that was marked on the map but that no one had visited for centuries. I told my minions to rebuild the fortress and await my return.
At level 8 or so the party found out that I was a Necromancer because I animated a foe we'd recently slain to help win a very close battle. I convinced them not to kill me outright and my backstory (which I will relate in a later story) was very different. They decided to keep my secret since I'd saved all their lives many times over and I swore to not use Necromantic powers anywhere that I would be seen.
Fast-forward two real-time years and our characters are high-level and very powerful. We'd fought demons, dragons, vampires, and all manner of terrible foes. We'd defeated armies and cast down evil empires. We could go anywhere and do anything…or so we thought. We talked amongst ourselves and decided to close the campaign down after one more grand adventure. The player running the Fighter pointed to the map and asked what the ancient ruin was. The DM explained that an evil Lich had resided there centuries ago but that a coalition of heroes and noble armies had formed an alliance and defeated him. His castle was a ruin and everyone avoided it. Noone had been with a week's ride of it for hundreds of years.
We decided that this was to be our last great adventure and promptly set out. We encountered several of the usual 'travel encounters' along the way until we reached a point about a week's ride from the ruins. From then on, the ride was peaceful and we were unmolested. When we were about three days' ride from the ruin, we began to encounter people. There were Humans, Halflings, Dwarves, and Elves, all living peaceful, harmonious lives. We asked them and they explained that the ruins had been rebuilt by a benevolent ruler who treated his subjects very well and kept everyone safe. They pointed to the fences that surrounded the pastures and we saw that they were made of Skeletons…stretching for miles.
Each Skeleton had a spear resting on the ground and the next Skeleton holding it, forming a fence of Skeletons joined by spears. Any time an intruder approached, the Skeletons would become animated and drive it away. So it had been for several years. The residents had taken a little while to get used to the idea but eventually, they got used to it. As we rode through the villages we spotted Skeletons doing all sorts of menial tasks like carrying water, sweeping out shops and handling tools. Some were repeating the same task over and over under the supervision of one or more living residents. There were even parts of Skeletons doing work. For example, the well at the center of each village had two skeletal arms attached to a crank. Whenever a townsperson stood by the well and said 'Water, Please,' the arms would turn the crank and raise the bucket. The blacksmith had two Skeletons swinging hammers to help him forge iron and the plows were even pulled by the skeletons of oxen.
Despite the creepy surroundings, everyone was happy. We talked to several people to make sure they hadn't been coerced or controlled in some way but all of them were normal. They raved about their noble lord who only charged minimal taxes and always protected the people from bandits and wild animals. Finally, we decided to see this lord for ourselves. We road to the castle, which was no longer a ruin, and found an army of undead workers repairing it. They came in all shapes and sizes from Skeletons to Ghosts (who flew through the walls to inspect them) and even skeletal giants. We approached the main gate and were received by a skeletal doorman who asked us to state our names and our business. We explained that we wanted to meet the lord of the castle and he led us inside.
The inside of the castle was plain but well-built by the Dwarven Skeletons moving about the place. Wights acted as middle managers and there was a Vampire sitting on the throne directing all of the activities. We approached and he asked us who we were and what we wanted. We explained that we'd heard terrible stories about the place but were surprised to find the ruins repaired and the people happy.
Then came the big reveal. My Cleric/Necromancer said the phrase that he'd coded into all of the minions to identify himself and the Vampire immediately left the throne and kneeled down. With the rest of the party gaping in surprise, I ascended the stairs and took the throne. None of them had even suspected that this was all my grand design to build a nation that would not simply assume that Necromancers were evil.
We concluded the campaign on that note with everyone expressing surprise at my deception. It was great fun for all of us, particularly the DM who had been in on it from the beginning.