I don't really give much weight to zodiacal signs when chosing my characters' birthdays, I tend to instead either hide references or simply go with whatever feels "right" to me.

Sergio, being born on October 27th, is a Scorpio. Which quite fits with his characterization, too, but it shouldn't be a surprise since he started off as my self insert and his characterization started off literally as Fictionalized Me (and thus shares my birthday, and yes I am said to really behave like a Scorpio),

Nikki, as she is a badfic clone of Sakura Kinomoto, shares the latter's birthday which is April 1st. As such, she's apparently an Aries, though she doesn't seem to share much in the way of that sign's associated traits, and her "template", Sakura, does even less! CLAMP surely chose April 1st with a different type of symbolism in mind.

Corolla is a bit of a peculiar case. Her birthday is (officially) May 25th, which is around the day I discovered the PPC. As an Unison Device from Lyrical Nanoha applying Earth-based astrology to her makes little sense. Still, she's a Gemini, and that sign still kinda fits with her.

Ami was born on December 28th, so she's a Capricorn. I felt that a birthday towards the end of the year fit with her, but she does seem to share some of the Capricorn's traits.

Keiko's birthday is just two weeks after her mother's, on April 13th, so she's also an Aries. I dare say it fits her better. Hajime shares her same birthday, being literally her alternate universe incarnation, but like Nikki doesn't really incarnate an Aries much. Their birthday is a reference to the day Mai Dire Fine, the fanfiction where it all started, began.

Kathleen was Aelit's self insert in Mai Dire Fine, so she shares his birthday which is July 31st. As such, she's a Leo which also kinda fits with her.

Faith's is on February 13th, chosen to be a rough inversion of Kathleen. That's Acquarius, which like Nikki is a complete miss in traits.

Fun fact: some of the bits associated with Sergio and Nikki are interesting. Their signs share the same ruler (Mars) and detriment (Venus), but their signs' element are kinda inverted between them. Sergio's sign, Scorpio, is a water sign and such associated to "emotion, empathy and sensitivity" while Nikki's, Aries, is a fire sign and such associated with "assertion, drive and willpower". Which, if you think about it, are kinda swapped between the two characters!

I did this with Nume. I decided he's a Scorpio, then set his birthday on November 10, 1950.

Gall is the very definition of a Leo, which would put her birthday sometime from July 23 to August 22. I haven't pinned it down.

Jenni has multiple birth dates, not all of which took place on Earth, but I usually make it the first day of spring or spring equinox. For instance, in the Purityworld deconstruction, it's March 20, 1960, which makes her a Pisces on the cusp of Aries.

Ilraen and Derik weren't born under a Terran sky, so our astrology isn't really applicable to them, but just for fun: Following the rule that partners should be opposites, Ilraen could be a Taurus and Derik could be an Aquarius, but I'm not convinced. I'm pretty sure Ilraen is not a Sagittarius, as amusing as that would be—but Derik might be! I dunno, I'd have to look into it more, and I'm all out of time for tonight.

~Neshomeh

...I have now decided that Mina’s birthday is September 28, so she’s a Libra, and Carlisle’s is January 2, making him a Sagittarius.

Yeah, I had to look up the Zodiac.

—Ls

Rebecca Buch, hmmmm. I haven't given her a birthday yet, but why not May 25? It is a nerdy sort of day. She's a Gemini, but she thinks that horoscopes are probably a load of rubbish. Any supposedly Gemini-ish traits she has must be a coincidence, she swears.

Deirdre is not from anywhere that has the zodiac. She lives on Deveb V, which may possibly be a planet which exists in the real world, but is probably not habitable if it does exist. She was born on XIII Arctus, which is near the winter solstice, so Sagittarius, I think.

Boadicea probably doesn't have one because of the whole respawning after death thing, which makes it hard to calculate. Does the day she respawns on count as a birthday? I don't think it does. It would make things dreadfully hard to calculate. I think she is an adult, but she could be several thousand years old because of the respawning thing. I think this could be called pseudoimmortality. She probably doesn't look like she's several thousand years old, but she's definitely not young and pretty either, what with spending all of her life in Terraria fighting monsters.

Edit: fixed typos

The Cancer sign is ruled by the moon. Guya was conceived on tsukimi and is named after a folklore character from the moon as a result. So there ya go.

Zara is a Virgo, Doom is a Scorpio, Diamond and Thalia are Gemini, and Meg… is part of the Second Circle of demons. She doesn’t have a birthday.