It is in my nature to automatically "put myself into other people's shoes", as my mother (a wise Sagittarius lady) taught me to do from the time I was born.
I can't imagine people who don't, but I do see this everyday.
 
I checked my Dwad placements just for fun, and find that my Dwad Rising Sign is 23 Pisces,
as is my husband's Dwad Sun at 23 Pisces.
I suppose it goes rather well with our similar Cancer placements, (his the moon, mine is Rising both in Cancer)
 
I can't fathom or understand people who have no hearts. But I see it all the time.
 
as for Joseph Mengele, who had Pisces at the MC 24 deg.,1st planet to rise in the 12th when he was born was Pluto, with Neptune in Cancer in the 1st house; there are many mitigators in his chart to be taken as a whole.
 
Linda Goodman once wrote that the Pisces child who was neglected,(and I think Cancer children too?)
can be some of the more notorious cases of good gone bad. Potential good that is, because of the great sensitivity nature that is born here.,that IF they have parents that abused, hit or weren't keyed to their children's sensitivities, they can then turn around and be some of the most heartless, obnoxious angry human beings on this earth.
 
The study of serial murderers, brings out many many Pisces & Cancer Sun & Moon positions which seems to verify Goodman's opinion.
 
It probably would have been good to study the charts of Mengele;s parents too, but we only have his own.
As such, I see that he had Moon in air Libra; in the 4th house of  home, and it was the only aspect to the moon being square to Neptune.
 
I think Neptune can be seen as a secondary ruler of Cancer? his rising sign........hence, they are not in good stead at all from day one.
Here is a link about Esoteric Astrology and it's Rulers applied:
 
The Esoteric Rulerships of the Signs
http://www.aplaceinspace.net/Pages/CandyJourneyoftheSoul.html
 
These rulerships may seem odd at first, but a deeper study will reveal their significance.
 
Aries - Mercury
Taurus - Vulcan
Gemini - Venus
Cancer - Neptune
 
Other "mitigations" that I see in Mengele's chart would be the following:
 
Venus in Aries (it's detriment)
Venus square Neptune and Uranus
(potential for sadism)
 
Uranus also square to Saturn
Mars square to Saturn (speaks of cruelty potential from father)
Pluto square Sun & Mercury (   "     "           "          "     "     )
 
Jupiter near the critical 15th deg.of Scorpio 5th house conjunct his South Node.
 
All of these things must be taken into consideration and not just that he is a Sun Pisces.