I can try to help but there are others who can probably explain this better or know more than I do. Sun, pluto and mercury to the MC in scorpio?So MC Scorpio is death , rebirth and transformative. If you've ever experienced a pluto of someones on one of your personal planets you'll know it is a type of energy that will stir you up emotionally, physically and mentally. Atleast that has been my experience but I think I am a plutonian type person.
So I'm not sure how to explain it other than tell you what the things mean and then put them together by that.
Composite chart means from my understanding how the relationship acts as a third party and how others see the energy?
MC of the chart is the public image of the relation? ( composite)
Sun, vitality, soul , who we are ( composite?)
Pluto, transformation , death , rebirth
Mercury, communication