Imagine each three signs of the same element (Fire, Earth, Air, Water) as the three siblings

I'm the oldest, I make the rules:
Leo| Taurus |Libra| Scorpio

I'm the middle one, I'm the reason there are rules:
Aries| Capricorn |Aquarius| Pisces

I'm the youngest, the rules don't apply to me:
Sagittarius| Virgo|Gemini| Cancer