Some ideas on changeling society borrowed from: [link]
Mother of Chrysalis, and former queen of the Changeling Hive.
The way a Queen functions in Changeling society is much different than in pony society. The queen functions as a military leader and as a center of the hive mind. Once or twice a year, the queen will really gorge herself on love to prepare for birthing more changelings. During this time, she is very vulnerable. No mating occurs. The queen is completely autonomous and could in theory start a new hive from scratch, though she'd need to suck at least one pony dry of its love (thereby also providing a first husk/worker for herself). “Suck dry” means that at some point they have turned into husks that live in a constantly hypnotized state and will only serve the queen. Their kind of love doesn't provide nourishment for the changelings. Once she has laid a clutch of eggs, she is done for the year, and the changelings in charge of the nursery take over from there. A queen will function for hundreds of years, and has no set death age. Once she is ready to move closer to leaving this world, she lays one single egg, which hatches into a young baby queen, and the current Queen raises her until the young queen decides she yearns for power, and murders her mother, devouring her love and birthing the first clutch of the new hive age. It's a pretty gruesome system, but its functioned for millenia, and even if the young queen refuses to usurp her mother, the maturing of the young queen releases pheromones that cause the current hive to follow her, and as such, they will consider the old queen an intruder and either evict them or murder them for trespassing.
Ok, so now let's talk about Vespa herself, now that we've discussed changeling society. Queen Vespa ruled the hive for over 1000 years, and went down in history as one of the most successful conquerors in recorded history, enslaving entire cities and using them to build a huge kingdom for her subjects. She had a more grandiose worldview than her predecessors, who only focused on surviving. Vespa looked at the use of their husks as small minded, believing that they could be used as more than hive workers and food. She murdered her mother as soon as she could, her mother was simply an obstacle to power. After that, she studied the other nations of the world, and infiltrated a small pony empire by killing and replacing their oldest princess. By the time they noticed, she had already taken over enough ponies to overpower their army, setting about to build their kingdom up from the one they had taken over. She instilled these dreams of grandeur and conquering into her daughter, grooming her to be the next step in the cycle, training her for the eventual day she would be succeeded. She watched her back carefully each day as it grew closer to the day she would attempt to usurp her. She secretly hoped that her daughter would be able to catch her off guard, and Chrysalis succeeded, by transforming into one of Vespa's caretakers, and waiting until she was to help her groom to strike.[link]