All the chart factors are important in synastry,
but there are particular factors that are critical in terms of relationships.
Below is a discussion of some of them.
Sun
& Moon. The Sun & Moon are the
most essential factors in natal charts, so obviously that will be the case
in chart comparison as well. Since the Sun represents our basic selves,
Sun-Signs in conflicting aspects between charts (i.e., his/her Sun is in
Leo square his/her Sun in Scorpio) suggest some essential difference in
personality and thus the likelihood of conflict. Imagine Leo, who
loves attention and likes to be open, trying to get along in a relationship
with Scorpio, who prefers to be secretive and self-protective.
Since the Moon represents our childhood patterns and unconscious needs, Moons in conflict would be a very difficult factor to overcome in a relationship. Let's say Person A has the Moon in Aries. S/he wants and needs excitement, change, even danger. If Person B has the Moon in the opposite sign of Libra, s/he will be appalled at the Aries Moon's unconscious needs, since s/he will want peace, harmony and quiet. Person A will likely pick fights just for the adrenaline rush, while Person B will have his/her entire equilibrium upset by conflict and will not want to argue.
If one person's Sun conflicts
with the other person's Moon, you have a similar potential problem.
The Solar person may be more conscious of what the problem is and the Lunar
person may not clearly understand the problem, but the problem will likely
exist regardless.
Venus
& Mars. Venus & Mars are, of
course, the planets of love and sex. Venus is what we desire in love,
and Mars is what we want in our sexuality. If these planets conflict
with themselves or each other between charts, there will obviously be problems
to be overcome in the relationship.
Let's say Joe has his Venus in Cancer, while Jane has her Venus in Sagittarius. Joe wants to nurture and be nurtured, and may be a little needy in his idea of love. Jane, on the other hand, is an adventurer, and wants her space and freedom in relationships, along with a spiritual and probably intellectual compatibility. How will they solve such an essential difference in what they want from love? This is the challenge they face.
What if Jane's Mars is in Aries, and she meets June, whose Mars is in Aquarius? What Jane wants out of the expression of her sexuality is fulfillment for herself, and a sense of adventure (Jane is apparently a very adventurous type!). June has Mars in the experimental, open-minded sign of Aquarius. What they are seeking in terms of sexual expression suggests that Jane and June would be a good match for each other in this arena.
The
5th & 7th Houses. The 5th &
7th Houses are the relationship houses of the zodiac, representing love
affairs (5th) and marriages/committed partnerships (7th). One partner's
planets falling in the other's 5th or 7th houses can indicate a romantic
and/or committed relationship. The signs that are on the cusps (edges)
of these houses indicate what each person is seeking in relationships.
Further, the house that the ruler of the sign on the cusp falls in may
indicate where you may meet potential partners and lifemates.
For example, Harvey's Venus falls in Amanda's 7th house of committed relationships. If other factors between the charts agree, this could be a good indication of a long-term romantic relationship.
Now say that Jim's chart has the sign of Taurus on the 7th-house cusp. Taurus is ruled by Venus. The planet Venus falls in Jim's natal 11th house of groups and friends. It is likely that Jim may meet a potential partner through friends or a group he belongs to.
Mike has Virgo on the 7th house cusp, while John has Capricorn there. Might they become involved? Possibly, because both have earth signs on the 7th house cusp, so both are looking for some similarities in terms of committed relationships.
Saturn.
I believe that Saturn is very important to consider in synastry, as Saturn
rules the archetype of the father (as the Moon rules the archetype of the
mother). It also relates (like Chiron) to where we have been wounded
as children. These deep needs are almost always played out in our
adult relationships. Saturn can show us where the most likely pitfall
in a relationship might be.
If someone with Saturn in the 3rd house, for instance, was attracted to someone who was extremely intellectual and intolerant of those who could not keep up with him/her, this relationship probably would not work. Why? Because a third-house Saturn tends to make one feel insecure about one's intellectual abilities. Clearly the intellectual would constantly remind (unconsciously or not) the Saturn in the 3rd person about his/her deepest fear.
A partner's Saturn falling
on any of your planets, particularly the above-mentioned critical points,
can have a detrimental effect on a relationship. Saturn is the planet
of restriction, among other things. If your partner's Saturn falls
on your Mars, you may feel like your sexual expression is restricted.
If the other person's Saturn falls on your Venus, you would be unlikely
to feel the love you need from the Saturn person.
This derived chart gives a portrait of your relationship as a separate entity expressing both of your unique characteristics. Relationships are formed between two individuals, yet the relationship itself is a third being. The composite chart gives you an idea of what you are as a team together. Transits and progressions to the composite chart can also mark important times within the relationship itself, when events affect both of the parties involved.