I like the idea of each planet having a “night and day” ruler, it’s so cute, like
Gemini is the day ruler of Mercury, Virgo is the night ruler of Mercury
Libra is the day ruler of Venus, Taurus is the night ruler of Venus
Aries is the day ruler of Mars, Scorpio is the night ruler of Mars
Sagittarius is the day ruler of Jupiter, Pisces is the night ruler of Jupiter
Aquarius is the day ruler of Saturn, Capricorn is the night ruler of Saturn
Leo is the Sun (day), Cancer is the Moon (night)
The feminine signs are the night rulers, the masculine signs are the day rulers; masculine signs are more comfortable out in the daylight, the spotlight, when everyone else is able to see them shine. Feminine signs are more at home during the night, it is their sanctuary, they express their energies more naturally when they are soothed by the mystery and tranquil solitude of the night.
And then you have the case of the few other planets that are only ruled by one sign. Aquarius is the sole ruler of Uranus. Their Uranian qualities are present no matter what, it is part of their kooky persona. Pisces is the sole ruler of Neptune. The Neptunian influence of illusion and fantasy is something that hangs on to Pisces every second. Scorpio is the sole ruler of Pluto. Scorpio can’t escape Pluto. It is following them around through every suspicion.