Hi Everyone and thanks for letting me join in!
Looking at the chart of someone I've known for a long time, almost 20 years, I noticed a disturbing aspect and was wondering what other people thought.
This person has an exact grand trine of Sun, Moon and Nessus retrograde.
The Sun is in Aquarius in the eighth, Moon is Libra in the fourth (conjunct mars in virgo!) and the Nessus r is in the twelfth. Nessus r is also square Saturn in Pisces on the MC.
What do you make of a grand trine of the lights with Nessus r in the 12th house?
Hi, inanna!
I don't have a clear idea of how Nessus works in action, in real life. Still don't, after reading what I know to be a terrific source -
http://www.zanestein.com/nessus.htm
The water houses all involve The Deeps in various ways, and Nessus matters seem to be deep and murky (life-and-death serious), at least. Grand trines can be talents taken for granted - a talented musician who rarely practices, e.g. Air signs for both who the person is, and their feeling nature (needs). Also, Rising sign is Cancer? If so, chart ruler - by the rule of thumb used most often - is Moon (in Libra, conjunct Virgo Mars - a dedicated loyal friend?).
Tell us what stands out for you, in your interactions over the years, with this person?
PS This link from the above link, is equally fascinating:
Well! What a delicious bunch of reading - says Gemini Moon in 9th.
For anyone who enjoys a concise summary in the mix, this one is even timely (see Elsa's blog about Pluto stationing & turning retrograde yesterday, April 20 2017).
http://wiki.astro.com/astrowiki/en/Nessus
Nessus - dirtyied by circumstances, guilty of actions/ reactions motivated by deep feelings, etc. Dark, yet, better to acknowledge than to ignore.
Thanks, inanna! 
Hi Poppy 
Thanks for your response!
The rising sign in this chart is in Gemini conjunct north node. Ruler Mercury in Capricorn in the 7th conjuncts Venus and Juno and Dejanira!
My take on this person is very dark and I am usually a happy Sag rising so I haven't wanted to see a lifelong friend as a dark person, but I have seen some clear patterns over time that were unignorable, and then I noticed the Nessus r placement.
While trines can be talents, they can also be like running around in a feedback loop, where it is easier to just repeat a pattern than to change. Likewise, an air trine, perhaps could be about rationalisations as much as clear thought.
But perhaps what makes this Nessus so dark is being retrograde in the 12th? Definitely "guilty of actions and reactions" most likely "motivated by feelings", as you said.
The pattern I see is long term and repetitive abuse of power through romanticising, emotionally seducing and discarding women, while being completely unconscious of any culpability although he is married and in a position of trust. So, perhaps covert narcissism or love addiction, though I'm not a psychologist! I can only name the behaviour.
With the Gemini Ascendant, great gift of gab and one face for his wife and another face where he tells his girlfriends bad things about his wife to make them feel superior. As I said, a very distasteful situation.
What got me really curious was how having both the Sun and Moon in a closed aspect, even a trine, could bring that third planet in as almost a "who a person is" kind of thing, even if they don't know it as it is hiding in their 12th, because of the 12th being the house of self undoing behaviours and all this hidden drama going on. Yes, from a purely intellectual exercise, it is one interesting chart!
And thanks for the links. I'm going to go check them out now
Depending on how big the orb is, the Nessus is at 3 Gemini and the ruler Mercury at 11 Capricorn conjunct a stellium of Venus at 11- Juno at 10 and Deianira at 7...that could be considered a quincunx.