Interesting thought that came up when talking about changeling Queens and Papi’s canon. When a Queen converts a pony they do so through the Queen’s Kiss, through which the Queen feeds the pony a modicum of her essence and love to make the pony hers.
A clever unicorn, or other pony having taken the proper potion(s), could potentially lock a Queen into the Kiss and force her to continually give up her essence to the pony. Rather than making them into a drone, this usurping of power would make the pony into a new Queen, and reduce the old Queen to a drone for the new.
This event, the Queen’s Kiss Rebound, has never been done, or at least recorded, in Papi’s canon but could be possible and warrants further thought.
The idea of Papi (or one of the other Queens) having the royalty effectively sucked out of her by a usurper she trusted enough to welcome into her hive, and leaving her a drone and subject of said usurper is legitimately fascinating to me. I may need to experiment with this, but would first need one who would ask to be a drone, and make themselves a Queen through deceit.