Some of the Synastry aspects between me and my Cap include:

• My Mars sextile his Sun 
• My Mars trine his Moon
• My Mars sextile his Lilith
• His Mars trine my Venus
• His Mars conjunct my Neptune by degree
• His Mars sextile my Pluto
• Mars square Mars 
• Rulers of our respective 8th Houses conjunct

He's the person with whom I found myself most compatible and comfortable during sex. The sexual chemistry is mind-blowing, we're both insanely attracted to each other. He also has his Eros falling in my 8th. 

Another example is my previous boyfriend and former best friend, a Pisces. The sexual activity in the beginning of our relationship was rather intense, but with no actual involvement on my behalf. I was still heavily suffering from BPD and sex was more like a manipulative and cathartic act than actual intimacy. 

• Mars conjunct Mars
• His Mars squaring my Saturn
• My Pluto trine his Sun

Pretty soon I started to grow weary of physical encounters with this person and his very touch and closeness started to aggravate me. 

With this other man I had an affair with, my Mars was exactly on his Sun, and his Pluto on my Sun, but -- sex was mediocre and very disappointing. 

Venus in Aries (his) mashed up with Mars in Aries (mine). Heh.

hi mermaid great question!

......I can add to the recipe : mars opposite mars, venus trine mars, venus conj. ascendant, mars conjunct ascendant and the big Kaboom: lilith conj. moon and lilith conj. sun/jupiter

have fun...

I think mars square saturn, in rare instances can be really good... When its bad its reallly bad though...

But there are certain complicated situations where it can be good... And of course it depends on each individuals birth chart...

But yes, in my case, being the mars person...and being very very marsian(is that the word?) to begin with, it does not work for me... But I imagine mars square Saturn can actually benefit people in certain instances...

Just like any square in synastry... They aren't bad persay... They create learning experiences and sometimes learning experiences are lifelong lessons. sometimes squares create just enough tension to make things work because without them, a person without that tension would be lost. if there is the tension with the exact right amount of other support in the chart...it makes relationships really beautiful... I don't think Saturn squares are bad 100% of the time.

Did I mention I like mars sq/opposite Pluto.... Lol... This is not bad for me...for other people it is...but not for me... I'm so mars/Pluto already, the Passion/drama is ideal for me... I can handle this aspect like second nature... Not mars Trine pluto...I really need stimulation that's more primal and creates friction. Especially because my Saturn conjuncts Pluto and opposes mars in Aries... This is something I could do permanent and make it work, lol.