Authors note: This one is a single shot, head cannon shedding some light on the odd living styles of the Silver Millennium, including why the Princess's seem to be named after their planets. Didn't include Shitennou as characters, as they're really only there to tell the story. There will be another part, so to speak, probably of a similar name. It'll be a story, possibly multiple chapters, on the early life of the Shitennou.
The lifestyle of the other had always confused the protectors of the Earth Prince and Moon Princess. However, this seemed even more true for the protectors of the Prince. The people of the Solar System seemed to have a fair idea of the workings of Earth, but the humans of Earth hardly knew where to begin in understanding the lives of the protector's of the Prince's darling Moon Princess.
"If you're a princess, why are you working as guardian's to the Moon Princess?" Jadeite had asked the group of Senshi once, upon one of their many errands to Earth trying to find their princess.
This question seemed to insult every one of the Moon Princess's protectors. Venus turned her nose into the air and answered, "I'll have you know it's a tremendous honor to guard the Moon Princess. I shall perform my actions until the Princess comes of age and becomes Queen, just as my mother, Queen Aphrodite did before me and her grandmother before her."
Kunzite shook his head at the forwardness of his comrade's questions. Much to his chagrin, Jadeite wasn't finished either, "Well then, why are you named after your planet?"
Venus had blinked tilted her head, confused for a second but much less insulted by this question, then she rolled her eyes, "We aren't named after our kingdoms. You humans named our kingdoms after us. I'm not Princess of Venus or Princess Venus of Venus. I am Princess Venus of Magellan."
"You know, you humans used to call my planet Aphrodite, as well. You call it by what you know it, not what it is. You're quite arrogant to never ask its actual name, you know," she finished, crossing her arms.
"Silly humans," Mars had muttered, also rolling her eyes.
"To be fair, you're planets have been named so since before we were born around 20 Earth cycles ago for each of us, even Kunzite who was born earlier," Nephrite stepped to the defense of, not only his brother-in-arms, his species
"Well, of course. They started calling it so around our inauguration as the protectors of the Princess fifty Earth cycles ago," Mercury answered matter-of-factly.
"Fifty…?" Zoisite muttered, voicing the shock of his companions while eyeing over the beautiful and quite young looking Mercurian.
None of the Shitennou really grasped the strange ways, or life spans, of the "outsiders" at that time. Nor, honestly, had any of them really wanted to do so. Today, each of the girls were sure, would be no different if the Shitennou were around to question them more.
These days, the planets were called the same names as the scouts. The humans had latched onto the names of the last Senshi, remembering little else of the kingdoms and their people. They became myths and then almost forgotten entirely as they actually were, instead eventually becoming the Gods and Goddesses of the Greek and Roman worlds.