Most people know that they get on well with others who share their sign or element, i.e. Aquarius and Libra, Taurus and Capricorn, etc. The flow of communication between you will be easy. You won't have to try hard to understand each other as you are generally on the same wavelength. But sometimes you meet someone who you know you should get along with but you don't. This is because when it comes to the interaction between people, there is more to it than just Sun signs.
There's a section of astrology called synastry which deals with compatibility and it shows how people interact with each other by comparing their birth charts. Have you ever wondered why you like someone a lot? Or why you can't stand someone? Why a person you have just met for the first time feels like a long-lost friend? Synastry has the answers. It's so accurate that if you take the charts of a group of people who have never met before, you can predict which ones will end up becoming friends, lovers - or even enemies. Very revealing!
Synastry is used to analyse all relationships - or potential relationships - not just romantic ones. Friends, business partners and family members can all be studied in this way and it's fascinating how people are connected to each other astrologically. I mentioned in a previous post that certain astrological traits are somehow duplicated in the charts of family members. There are always strong links between the charts of people who are related to each other. It's not a copy - every chart is unique - but one person's Sun sign could be another's Moon sign, or someone's Rising sign might be the same as someone else's Rising sign. For example, I have noticed that, in families, the Moon is often in the same quadruplicity or the same element throughout the family. Another interesting observation shows that relatives often have the same planets in aspect.
It's important to mention that Synastry shows the astrological connections between people. Other techniques such as the Composite chart actually analyse the relationship itself. It's interesting that two people can have brilliant synastry connections but when they actually get together as a couple disaster strikes. The relationship they create together just doesn't work. The Composite chart would show this. It represents the kind of relationship you have - or will have if you become partners in some way, romantically, professionally, etc. Synastry reveals the chemistry between you and the Composite reveals what will happen when you mix it together!