Well as it's all a part of a fictional Alternate Universe it can really be whatever the mood strikes me to be. But because I like to pontificate and haven't actually started posting this particular AU fic yet I'll detail my reasoning here.



All of the Senshi in this version of the Silver Millennium are of their planets Royal house. The Silver Millennium as a whole have a polytheistic religion but the patron deities of the planet are held in higher regards on that particular planet. As such names on the planets tend to trend towards stories involving the planets patron and things they like, this goes doubly so for the Royal House. In the Silver Millennium there is no Roman or Greek, those are societies that evolve much later on planet earth and are echoes of the societies that were once found on the planets. To interchanging the "Greek" and "Roman" names means nothing since in this AU that were all originally Silver Millennial.



So we'll start with Jupiter. Jupiter's patron deity is Zeus. So had the Royal house of Jupiter had a son they would have possibly named him Kiszeus (kis being a diminutive and Zeus being Zeus) or Tinia (which is the Etruscan counterpart of Zeus). But they had a daughter. Athena is the name I chose, because in mythology and her many titles include Zeus's favorite child. She sprung full grown from his head, after he attempted to keep her from being born afraid of the prophecy claiming any offspring from his union with the titian goddess Metis would be greater than he. So in the context of the only daughter of the Royal House of Jupiter, Athena is a popular family name for daughters to ensure their prosperity (and thus the kingdoms). Athena in the context of being the name for Sailor Jupiter and thus Makoto is because Athena's predominant role in Ancient Greece was the goddess of heroes, warfare, civilization, wisdom, and domestic crafts. The duality of a Goddess who is both war and valiant honor and weaving and pottery paralleled well with Makoto being both a fighter and someone who loves flowers and cooking. Moreover when I think of wisdom, I don't immediately jump to academics and scholarship but to common sense and knowledge through experience all things that I think Makoto is.



I freely admit to being less happy with the royal names of Mars and Mercury, but I'll explain why they are at present and may change in future.



Mars, Aries, a fire planet. By the reasoning above a daughter of the Royal House of Mars should be something like Alala (the daughter of Ares and the personification of the battle cry) or Harmonia (another daughter of Ares) or possibly Eris (sister and companion of Ares, Goddess of Choas and discord). I decided not to give our Sailor Mars those royal names. One because in my AU she is not the first born daughter, nor even the second born, and the farther from the throne the less important those connections get. Also because I wanted to set up her being slated to the priestesshood from birth essentially. So the name Vesta, has no correlations with the patron deity Ares, but it has a huge connection to the planets element fire. Moreover Vesta, goes kith and kin with the Vestial Virgins and is thus innately associated with priestesshood and the sacred fire. Hestia would be a goddess highly worshiped and regarded on Mars, being the hearth and home fire that mirrors the passionate raging fire of war.



Which leads us to Mercury. Mercury is a tough planet to choose a name for the Royal House heir, because it is the only planet in the system that over half the population is inclined towards atheism. So would the traditions of patron naming still take place in the palace? It would seem at the very least that it would be less important. Hermes is an interesting god to have as a patron anyway, with a wide gambit of fields in his repotoire it would be hard to pin down a name that would suit the Royal Houses pen-chances for efficient academic nature. Hermia perhaps. So I took a different root, deciding to go for Metis the goddess of wisdom, showing that at least her mother could think outside of the cold box that Mercury as a planet builds for it's women folk. I admit it's not the strongest reasoning of the bunch but I think it suits.



So there you have it. Not completely well reasoned out, but enough for me.