Outside of typical interpreting of real life birth charts, there is another method of using astrology that requires a bit of reverse engineering. I'll define it here as "fictional astrology", which is using astrology as a tool to better understand or to give more depth to characters.

The way I will be describing this method assumes that this character fits one of these categories, which they more than often do:

• They do not have a listed birth date.
• They have a birth date but with no year attached.
• They have a birthday with no birth time attached.
• They have a "sign" associated with them, but no birth date.

I think my title is pretty misleading, because not only do I believe that astrology can be used to create new characters, but it can also be used as a method of expanding upon already established characters. Just like how someone might create headcanons with using already established content or just out of thin air, astrology works similarly and can either be an personal investment where you find the most "accurate" chart, or you could play around with it and not be too pressed on the details.

As a personal example, I have done two charts for Edelgard from Three Houses. One chart is a hypothetical chart before I knew what her birth date was, which meant I went in blind and just went off vibes and how I believe her chart would be composed. The second chart I made for her was when I figured out that she does have an in-game birth date of June 22, and so I reverse engineered her chart with that information. (I fully believe she is a Cancer Sun, not a Gemini Sun. June 22 is one of those cusp dates where it's either one or the other, and I fully believe she is a Cancer in my personal headcanon.)

It is also exciting and fun to do charts for multiple characters and use that to further expand on their relationships. I am not going to go in-depth on synastry here, but just know that my stance is that I do not believe in "wrong" pairings of signs. I feel as if that's way too reductive of synastry, and if you see someone claiming that an Aquarius and a Cancer couldn't be a couple because they're incompatible (with nothing to support this argument and only focusing on their signs and not their entire character outside of astrology), then they are doing a disservice to themselves.

I also want to add that I don't really care about interpreting slow-moving planets. These planets (which include Neptune, Uranus and Pluto) are more associated with generations of people, rather than specifically influencing the individual compared to a fast-moving planet such as the Moon. The reason why some planets are fast and some slow is dependant on how long it takes for the planet to move into another sign. Pluto is so incredibly far away that it takes a decade for it to move around, which I often interpret as a larger undercurrent in the world, connecting generations with each other rather than specific people. Not to say it has no effect on an individual, but rather I'd imagine it more as the ground and environment that a house stands on, compared to the foundation and materials the house is made (which would be the fast-moving signs in this metaphor).

Jupiter and Saturn are a bit of an outlier too. Below, you will see they take around a year or so to get through one sign, which is slow compared to the faster planets, but still faster than those I just spoke of above. There are some occassions where I care about Jupiter and Saturn, but I would only really care about them if you are interested in those two planet's domains and how they would interact with the faster planets' signs. If you really want a full chart, go for it! I tend to make a full chart anyways because I don't like "unfinished" charts, but that is my personal preference. I think that the faster planets already have a lot to work with!

All this to say: The birth year of a character doesn't usually matter if you want to create their birth chart. There are numerous different starting points in which you can begin to backwards engineer a chart, but I typically leave birth year for last, just because it's much more easier to pinpoint the faster planets that align with each other rather than get stuck within a specific year, only to find out that the cusp for Cancer that year begins on the 21st rather than the 24th, leaving you with less options of Sun plus other fast-planet combinations.

Also, depending on how much you really want to stick with real dates, you may not even care at all about getting an "official" birthday for one of your characters, because either the date is weird and doesn't fit with canon or the year where all the planets are aligned are in the 16th century and your character's living in the future. You can almost completely disregard the portion where you find the "real" date.

On the flipside, you may be creating a fictional world yourself and want to use astrology as a tool to set the stage of your world. In that case, I think it would be very cool to try to incorporate a "real" date that involves the slow-moving planets. I think to set aside the possiblity that you may get a 13th century date can be resolved by making a "fictional" calender where that 13th century date (in our real world) is translated to the year 2010 or something like that (in your fictional world). It's all just planet alignment after all, and time is fake anyways.

In the next few sections, I will describe how I would go about creating birth charts for a character depending on what information was already given, as well as a breakdown of the most important concepts that need to be remembered when making a birth chart.

It's weird to say that astrology has rules, but a better way to describe this section is that planets themselves have their own rules. They all have different speeds, and are also visible in the signs in certain positions. I will break down the key things to remember in a chart:

• In the course of 24 hrs, the Ascending or Rising Sign goes through all 12 signs.
• The Moon moves to another sign roughly every 2 and a half days. It rules Cancer.
• The Sun moves to another sign after roughly 1 month. It rules Leo.
• Mercury moves every 2 months unless it's in retrograde, which prolongs its stay to around 7 months in one sign. It cannot be further than 28 degrees from the Sun. This means a Cancer Sun - Capricorn Mercury cannot astronomically exist. The method I use to remember this is that Mercury cannot be further than 1 sign in relation to the Sun. So if I'm a Aries Sun, I could only be an Aries Mercury, a Pisces Mercury or a Taurus Mercury. This is easier to understand when you look at an astrology chart. It rules Gemini.
• Venus moves around every 23 days, and is also never more than 45 degrees away from the Sun. This means that a Cancer Sun - Capricorn Venus cannot astronomically exist. An easy way to remember this is that it is never further than 2 signs in relation to the Sun. It makes more sense in practice. It rules Taurus and Libra.
• Mars moves every 1 and a half months. It rules Aries and Scorpio.
• Jupiter moves through 1 sign after 1 year. It rules Sagittarius and Pisces.
• Saturn takes 2 and a half years to get through one sign. It rules Capricorn and Aquarius.
• Uranus takes 7 years to get through one sign. It rules Aquarius.
• Neptune takes 14 years to get through one sign. It rules Pisces.
• Pluto takes 24 years to get through one sign. It rules Scorpio.

My very condensed and simplified "meanings" to each planet (up to Mars) as well as the Ascendant. I would highly recommend using the resources on the main page to gain a deeper understanding of each planet, but this serves as a good jumping point.

• Ascendant: The in-the-moment, impulse view of oneself. The quick mask in sudden situations. I like guessing Ascendants by asking the person to describe themself on the spot. An easy to accept self-view, compared to the Sun.
• Sun: Your "self", the version of yourself you work towards. It is where your identity is leading to. A sign where you find the most confidence by enacting it's traits.
• Moon: Emotions and emotional response. Your habits and subconscious thinking. How you deal with one's emotions.
• Mercury: Communication! Communication, communication, communication. How you process information and how you convey information.
• Venus: What you value, what you admire! Pleasure, love and everything to do with your tastes.
• Mars: Your drive and your energy. What makes you angry, how it manifests and instinctual action.
• Jupiter, Saturn, Uranus, Neptune and Pluto will not be described here, but the sites listed on the bottom of the main Astrology page have pretty good explanations on them!

Finally, we are to the actual method! This won't be a too long section, as it is very subjective how one goes about reverse engineering a chart, but I hope this helps visualize what a possible route may look like.

Characters with no set birthday can be one of the easiest or the hardest charts to create. It all depends on if you already have a solid idea for them, or you are just trying to get through a list of characters and they aren't your highest priority. In the other hand, a character that already has a set Sun sign is a little bit more easier to conceptualize their chart, unless their Sun sign highly constrasts their overall being, then you'll have to do some Astrology Gymnastics as I like to call them. I will describe these gymnastics later, but all in all, the overall method to fabricate a chart is a very "choose-your-own adventure", so don't be afraid of being "wrong". You can't really be "wrong", really, since this is your own fabrication.

Let's imagine I have a character called Fils. Fils is quite an introvert and a big homebody. Between her and another character, she's the serious one of the two. She also gets easily irritated and shows her emotions very outwardly. I know that she's a Capricorn Sun already because she was given the birthday of December 26.

I find that the easiest place to start is to brainstorm different Signs that they would have. I am not talking about specifically as a Sun sign, but in general what sort of Signs their chart would be comprised of. Are they more Water leaning? More Fire? Do you know that they have traits of a Libra but also seem very Scorpio-y? Go with your gut feelings and write them all down! If they already have a Sun sign decided for them, then this serves to help flesh out the other planets. It helps to write down a note of the different signs that you felt a draw towards and add in their different traits!

Fils is very serious and focused on her work, which is more of a Capricorn trait. I would also consider her having some Cancer qualities because she prefers to stay at home, but maybe some Scorpio because she's very secluded and private about her affairs? I feel like she would also keep long grudges much like Cancer and Scorpio. I think she has some Aries in her because of her sometimes rash decision making.

The next few steps can go in many different directions depending on how you want to proceed. Typically, I like fleshing out the Sun and Moon signs first, then the Ascending, then the rest. The reason being is because the Sun, Moon and Asc. are tied to easier concepts to visualize together compared to Mercury, Venus and Mars. Also, with the help of Tao Products, I prefer looking through them in order to find something that overall fits the vibe of my character. It just makes finding the Sun - Moon much quicker and to get to details easier.

Looking through combinations of Capricorn Sun with Scorpio, Aries and Cancer, I felt very drawn to the Capricorn Sun - Cancer Moon description and I feel as if it fits Fils quite nicely. Though, I do not think Fils herself would outwardly describe herself as easily emotional...so I wonder what her Ascendant would be? I feel as if she would describe herself as a plain-old person with no nonsense, so maybe she is a Capricorn Ascendant too?

Research at this point is necessary, and there is not much else I can suggest other than lots and lots of reading and interpretation. This is also where the mental gymnastics of Astrology can come in. If you have a character that has a birthday that you can't find yourself agreeing with, you may be interested in seeing if other signs in other planets can alter it. After all, an Aries Sun - Leo Mars person would act differently than an Aries Sun - Pisces Mars. I am using Mars in this example because Aries is ruled by Mars (another sidenote: it is important to know what planet rules which sign!). The Pisces Mars in this example would muddle the Aries Sun, causing more of an internal conflict because the Aries would expect to channel their Ariesness in their own home planet as well. Pisces Mars sits uncomfortably in the Planet of Action, compared to Leo Mars who is familiar with the Fire-y nature of Mars.

A lot of Googling for Signs in Venus or Signs in Mars will help in your journey to figure out just how these signs manifest in different planets. And if you are lucky, you may chain some together, such as Sun - Venus combinations.

Once you have figured out the signs you want for each planet, you're done! Well, unless you want to find a specific date, then Astroseek has an amazing backwards engineering calculator to figure out which day had exactly the planets you chose!

As a last example, I will be sharing a personal note of mine for a chart I've been currently working on. You can kinda see the process in each new iteration:

• Aries Sun / Sag Moon
• Aries Sun / Libra Moon
• Sag Rising / Aries Sun / Taurus Moon
• Sag Rising / Aries Sun / Scorpio Moon
• Sag Rising / Aries Sun / Sag Moon / Pisces Merc