(Looks like Jim had already posted a reply by the time I've finished typing this looong post, but here's my take anyway: 
)
Hey Mikestar,
Fellow forum member, Florence did a great job analysing the synastry between you and your son. You both have such a wonderful connection I don't seem to often find in other father-son synastries.
The Sun-Sun square shows the similarity and also the clash that comes from being too similar and yet very different. Both Sagittarius and Pisces are spokes and are traditionally ruled by Jupiter, hence they do share similar traits. You both also have Martial Moons and he has Neptune angular while you have a Pisces Sun—more similarities! But first and foremost, he's your son, of course he would be so similar to you.
His Jupiter to your Mercury shows that he values your opinions very much (most of the time, at least), he listens to you, and he is obedient to your requests and commands. Jim has found that Mercury-Jupiter co-aspects are very common between the charts of parents and children.
Though his Sun-Saturn trine seems to suggest that you're a little strict on him, though maybe not too strict (as it's a 3° trine), and his angular Neptune is suggesting that he's very close to Mummy too. (Unless you're his "maternal figure" too, showing constant affection and nurture.)
Is Joshua still in Torrance, or is he with you in Redlands?
Regardless, in both locations, his SSR features a Sun-Pluto conjunction on his Descendant (Sun is partile setting in both places) with a partile Moon-Saturn square that partile connects to his natal Moon as well
(0°00'!). He is very conscious of his goals and ambitions, but worldly pressures weigh upon him significantly. That Sun-Pluto
may mean that an unexpected shocking event will (or has) affect(ed) his life during the course of this year, where he may be left alone to face the music and guard himself. He is extra sensitive to his emotions this year, and he'd definitely love the support and warmth of his mother or a motherly figure he much respects (could be you too). He is strongly tuned to his surroundings too (and he already has sensitive Neptune on his natal Ascendant, moreover) thus is really happy when happy, and really depressed when sad. His Moon-Saturn shows that this is a stressful year and that he his holding up his feelings, maybe appetite too. Others or his environment may appear harsh to him, his health/vitality/energy is low (despite his Sun angular on the descendant) and his mother's health should be kept in check too.
Things may have been better when Jupiter's station squared his Sun this past May and June, it was a needed relief for him, and it brought much cheer, happiness and energy back into his life. Oh, and some prosperity too.
Currently Saturn is being conjunct his Moon, this is intensified with his current lunar return of 6th July, where in Redlands, has his Moon partile squaring MC and Saturn partile on the eastpoint. Your son is probably very much depressed right now, maybe much worried about Mummy too
but for reference, here's Jim's standard interpretation for the transit:
SATURN aspecting Natal MOON
A strong incentive to achievement and determined hard work. Emotional matters are likely more difficult, however. Practical concerns are easier to handle than those of the heart. You feel more vulnerable than usual, and more responsive to the harsh, demanding, unsupportive facets of your environment. Emotionally cautious, preferring the safety of seclusion to the exposure of participation, you dwell too easily on negative thoughts. Security is very important to you at this time. Deep, genuine feelings are more easily withheld or masked. Nurture needs are greater than at other times, but you may be less willing to accept this kind of support. Look, consciously and attentively, for the warm, caring, giving side of people to balance your temporarily narrowed window on others. The protection and certainty of a proper "nest" can be especially comforting now, and free your carefully warded feelings for your pleasure and others'.
IN BRIEF: Practical matters do better than emotional ones. Somber, distant, cautious; separation from nurturing; perhaps wounded pride, loss, feeling misunderstood. Security needs increase. Others seem unsympathetic.
His mother's health
may have worsened during the course of this return too...
Saturn-Moon transits have brought two long periods of sadness and loneliness to my life, once when I was 10, a Saturn-Pluto square connected to my Moon via the 45° and 135° aspects. My cousins who came to stay at my home for a week (which then became a month due to some reasons) finally went back home, and thus came a long period of loneliness. Being at home was depressing, at it was too silent. At school things were better as there were friends and company. The next one was at early 2014 where I was basically very insecure about myself and my body and thus another period of depression due to my insecurities.
This transit only ends by early this October. It'd be great if he has the support of his mother or a maternal figure (or at least a parental figure like you), and it would also be great if he sees his mother (and you too) being happy or optimistic despite you and your wife's health conditions.
The period between the 6th to 20th of February may have been harsh and sad/bad too, with Venus ~1° degree from the Asc in mundo and Saturn partile square the Ascendant.
Next year he has Saturn on SSR IC, but I believe this shows his growing and maturing up, getting ready for the outer practical world, though his home or private inner life could still may be in some trouble, and there may still be burdens and pressures placed upon him. But not everything is just grey, gloomy Saturn, there is some excitement and fun with his SSR Moon opposing his natal Uranus and squaring SSR Mars-Jupiter. And oh, some Jupiter transits once Jupiter enters Libra.
Regards,
TheScales_BothWays
Thanks for reading!
