Sun/Moon is the midpoint of heart and soul, right in between Sun and Moon*). It is the midpoint of motives. What is motivating you can be seen by the aspects of Sun/Moon. If it is Mercury, being the messenger might be your motive, see: http://astropost.blogspot.com/2011/04/sunmoonmercury-midpoint-combinations.html
What if it is Venus?
Venus is the symbol of grace, beauty, charm, peace, sweetness, style and diplomacy. You can imagine what happens when Venus is in hard aspect with Sun/Moon. It is the combination of the art of living, the desire to live in peace and being charming in heart and soul (because you want to be loved and probably ARE). To a Sun/Moon/Venus-person love is very important. With such a combination you are likely someone who is esthetic and maybe even an artist. Venus is a nice, sweet planet. Here only mistake is vanity and wanting clean hands. Do I have examples? Yes!
Umberto Eco: Sun conjunct Moon/Venus
Monica Lewinsky: Sun conjunct Moon/Venus
Casanova: Venus semi square Sun/Moon
Jean-Claude van Damme: Venus semi square Sun/Moon
Princess Diana: Sun square Moon/Venus
Queen Fabiola of Belgium: Sun semi square Moon/Venus
*) For more about calculating and interpreting midpoints, use this link to Astromarkt, the site with background info for this blog. In short:
The Sun/Moon midpoint is the equavalent of (Sun + Moon)/2. Of course, to calculate this you need to use the degrees of the 360 degree circle. A Sun in the 10th degree of Taurus is at 40 degrees, a Moon in the 20th degree of Libra is in the 200th degree. The midpoint Sun/Moon of this example combination is at 120 degree (zero Leo). If Venus is in the 1st degree of Taurus there is Sun/Moon square Venus. (Don't use more than 2 degrees orb).
Of course there is more in your chart than just Sun/Moon. But it is an important midpoint, because if you do have an aspect with Sun/Moon you won't be motivated if that aspect is missing. A Sun/Moon/Venus person won't be motivated much in a dirty, untidy or ugly environment or if there is no harmony at all, for example. And perhaps you, with Sun/Moon/Venus, tend to take care that things look nice and people are polite and everybody's happy and comfortable...When you look for a job, consider that. Sun/Moon/Mercury wants to have contact, wants to talk and wants to tell people about 'it'. Sun/Moon/Venus wants to have fun or wants to see style, all depending on the situation, conditions, character, and the rest of the chart. It seems to be strange to see a man like Jean-Claude van Damme (karate movies) in the list, but his mother was a florist and he (says ADB) married 5 times. Venus (beauty and women, entertainment and being an artist) in hard aspect with Sun/Moon apparently highlights all that is in the astrological vocabulary on V of Venus. And he looks good, too!:) 'Muscles from Brussels' of course has Mars (planet of manhood and muscles) elevated...
Also see Astromarkt, for example about Sun/Moon and AC/MC midpoint combinations. There you can read this about Sun/Moon and Venus:
Motivated for esthetics, luxury or entertainment (or love). The need to have fun and loving company...
If you are more interested in Sun/Moon in synastry, go here...
Also visit: Astromarkt.net