I think if the planets creating the midpoint are in aspect, that aspect can be a factor.
I more and more think that neglecting that underlying aspect might be a mistake. Perhaps midpoints are operating "on their own", but in truth I think (though cannot prove it of course), that the underlying aspect, if there is any (though using harmonic astrology, there is always a specific vibration, might just not be a Ptolemaic aspect), will colour the experience and expression of the midpoint very strongly.
But as I said, so far this is just a hypothesis of mine.
Saturn-Pluto is or could be harsh. Very true. I tis the "no dessert" combination (as Cochrane put it), "bare necessities", stripping away all luxury so to speak, no easy way out, if you did not do the work, you will pay for it.
However, I honestly believe, that there is some dark beauty in this scenario. stripping life of all the desserts/ distractions, gives you a keen insight into what you REALLY need, what is REALLY essential. We might not like what it brings up or what it strips away from our life, we might not like the harsh education it brings or the consequences. And there will be no cream on top, no sugarcoating, literally, and if it is isolated in a synastry or composite for example, it might really be just about getting through, going through the motion, keeping existence somehow together, without any emotional warmth or affection or whatever. However if it is connected to Moon or Venus, I do see a slight difference; well on bad days it might totally crush the sweetness and emotions in favour for "we do not have time for this. We need to focus on keeping life together somehow". But on good days it might lend an unspoken depth to love and relationships I think. Maybe one that is never really spoken about (Saturn and Pluto are both rather mute, not making too many words).
Also I read that some astrologer called it the "initiation midpoint". Well I found it, CArol Willis wrote: "My favorite midpoint is the Saturn/Pluto midpoint - I call it an "initiatory" midpoint, having to do with opening the door of the soul of the prepared aspirant to spiritual initiation, direct encounters with God/Spirit. Saturn/Pluto also seems to have a lot to do with good and bad karma, and karmic testing, especially in synastry. I recommend doing a mini or full retreat on the 3 days surrounding the transiting Sun conjunct the Saturn/Pluto midpoint: the day
of the exact conjunction, and one day on either side of the exact conjunction. Follow a simple, orderly, beautiful, devotional, inquiring and contemplative path at this time,
leaving much of time for solitude and spontaneity. These 3 days each year are outstanding for vision quest, ideal for teens age 16+ who passionately seek spiritual awakening and
understanding to be initiated. Uses of classical and traditional music, drumming or other percussion instruments such as piano, yoga, and being alone in nature may be helpful to create a suitable context."
my natal SAturn/Pluto-midpoint is on 28°01 Leo.
Sun is transiting that from 20th - 22nd august, though in some years it might also include the 23rd or 19th august.
I definitely noticed this to be a very intense timeperiod for me, less in the sense of retreat but more in the sense of lifechanging or insightful events or meetings taking place. .
Something materializing in the real world that gives me a lot food for thinking. lol For the recent years it was challenging, cathartic but positive, like putting some cracks in my solid armour and defenses.
But then again the time Tr Saturn was squaring my natal Moon, was outrageously .... progressive. Slow steady sometimes surprising changes of perspective. Like being shown another way of seeing things and that I might have seen them not quite right before, and that there are different interpretations and truths possibly at play. And just like Tr Saturn on my ASC, instead of isolating me, basically forcing me to interact with people, bringing people into my life, make me take decisions to step out of my little world, crossing borders, but in a quiet way of course.
Well 28 Aquarius is where my natal true Lilith resides.
My Solar return of december 2016 and covering most of 2017 had ASC on 28 Aquarius conjunct Mars on 28 Aquarius - it was a lifechanging year, honestly speaking. I changed my views and accordingly slowly developed a different kind of interacting with people, of acting towards other people. Instead of closing down as one woiuld expect with Saturn-Pluto, it forced me to at least put my head outside my shell a little.
Possibly for me the bare necessities involve the insight that I need other people. lol But I`ve always said I live my life in reverse order, like for most people the lower chakras are well developed and they need to open up the higher ones, and for me it always seemed that I have to limit a little the buzzing in my crown chakra or others, but really really have to work on the root chakra stuff and possibly sacral chakra, and to a bit the solar chakra. Of course doing that, the expression of the other chakras changed as well. It is just a metaphore I am using here btw. I don`t really think my crown chakra is well developed, it was just spinning out of control, and at too high a frequency (fast spinning), and every disbalance is a sign of not being really well developed; as there can be a too little, there also can be a too much, Neither is a good sign.