Wdyt the legion kids zodiac signs are? (Idk if you're interested in this but I found out that using zodiac signs for characters is a great starter... Like for building their personality).
You can do the main three (ascendant; basically what others get from their first impression of you. Like the personality you use out in public. Sun; your actual personality, the one you'd use around family and close friends. And moon; your inner personality, your feelings and secret traits that you wouldn't express openly).
I hope I explained these well enough and that it makes you think! (New Anon btw. Hello, mun!)
(I hadn't really contemplated this much until you asked, but I love thinking zodiac so I do have some solid answers:
Julie - Gemini Sun, Scorpio Moon, Pisces Ascendant.
Julie is both social butterfly and social chameleon. I think her place as the most social member of the group and how easily she lies and plays a different role in front of other people shoes her in for gemini easily, along with her curiosity and morbidity. While she seeks shallow pleasures for brief fun, what she really craves is emotional intensity, which I think plays with scorpio moon well. Pisces rising because of the strong association with art, social-chameleoning, and having a desire to see the world in and live in a dreamy and fantastical way.
Frank - Sagittarius Sun, Leo Moon, Aquarius Ascendant.
Frank hates routine and structure. He's friendly and outgoing, but in a way that still sets him apart from others. He's also very active and fond of sports, which is a stereotype associated with the sag lol. They're also associated with optimism, which I think plays interestingly with Frank's ideology that thinking about something is enough to manifest it. Leo moon is associated with controlling and organizing friend activities, which Frank definitely does - bossy guy, trying to push everyone to further extremes. He's a creative sort with a lot of magical thinking, and likes others to think he's really worldly and knowledgeable. He's paradoxically standoffish and social, but also very paradoxical and irreverent, which I feel fits the aquarius assignment well.
Joey - Virgo Sun, Taurus Moon, Sagittarius Ascendant.
Joey is a hard-working individual, but also a very practical and quick-thinking one. He struggles with anxiety and being high-strung, pushing himself too far. He's Responsible. All very virgo of him. With his moon, I think the taurean moon descriptions of like being very persevering, trying to avoid messy or unpredictable situations, wanting to build a reliable situation, etc. is very relevant to him. Sagittarius rising is often associated with Seeking, wanting more out of life, but also being opinionated and competitive, which I think Joey has a little bit of going on. Even though unpredictable circumstances cause him anxiety, he wants to branch out and try these new, crazy things anyways, and wants to have a good time, and more than anything wants to believe everything can be better if he just tries hard enough. There's a reason he ends up buying into Frank's ideology despite initial hesitation!
Susie - Taurus Sun, Cancer Moon, Aries Ascendant.
Susie is a very dependable person, but also someone I see as very stubborn and set in her beliefs. She's sensitive, but she's also very fixed - even upsetting her isn't going to move her, and may in fact fix her more firmly in place. For her moon, that sensitivity rings true. She doesn't like change and is defensive of her friends, wanting what's best for them, but is also indirect, not likely to confront issues head-on. I really like this screenshot of the natal chart website I'm looking at for her:
Speaking of family problems, aries ascendants are often described as having an upbringing that requires them to learn to take care of themself. Impatience and impulsiveness and a youthful charm are also part of this sign. I think Susie isn't necessarily competitive but definitely has a compulsion to "prove herself" and an amount of self-criticism that tracks well with this ascendant placement.
Sorry to anyone who doesn't care about zodiac who had to read all this LOL)