Have an Illager Spy

There is a very low chance of having an Illager spy spawn in a village. It could have a slightly greyer skin color, blue/different-colored eyes, or some other Illager-related trait. They become hostile if attacked, but the iron golem will help them and attack you. During raids, they attack villagers and the iron golem. Hostile mobs also do not attack them. They also sound like Illagers, and they have Illager spy children. Illager banners can be used to slowly convert villagers to Illager spies or Illagers. Whichever is decided. They drop an Illager banner upon death. There can also be entire villages of them, which are Illager Villages, and are even rarer. This could become an engaging joke in the community, where they're trying to root out the spy. Spies could be a feature where people don't realize it until they eventually get attacked, creating a shocking and funny moment. They could also avoid the golem or something normally, which would also be funny.