"Right now those people are also living inside the Abyss world with those Abyss humans. You can say they were the subordinates of those abyss humans. I also got to know that this person not only came to the real world but at the same time many people like him also came to Terraria. Unfortunately those people are not only present in just one Kingdom.
Most likely you can say that they are the spy of those Abyss humans. Because they could also use the dark spiritual energy so instead of those Abyss humans, these people are the one who created those previous teleportation arrays inside our territory. Because they are humans we naturally ignore them and do not check that much. So using that as their advantage those people previously entered in our Kingdom and at the same time created those teleportation arrays with the help of those Traitors.