What it does to a planet
Scorpio intensifies and conceals at the same time. Mercury in Scorpio investigates and does not share what it found; Venus in Scorpio attaches completely and slowly; Mars in Scorpio is strategic rather than impulsive and has an extremely long memory for who did what.
The concealment is worth naming, because it is often mistaken for dishonesty. Scorpio withholds by default, on the reasonable assumption that information given away cannot be taken back.
Fixed water, which is unusual
Water signs feel; fixed signs hold. Scorpio does both, which means feeling that does not pass. Cancer retains its experiences and Pisces disperses into them, but Scorpio keeps its feeling at full strength for as long as the situation warrants, and sometimes considerably longer.
This is the source of both the endurance and the difficulty. A Scorpio placement will outlast almost anything, and it will also carry something that should have been put down years ago.
Two rulers
Traditional astrology gives Scorpio to Mars; modern practice gives it to Pluto. Both are worth checking. Mars describes how the placement acts and fights; Pluto describes what it is trying to get to the bottom of. Charts where Mars and Pluto are in very different conditions produce Scorpio placements that behave inconsistently, and the inconsistency is informative.
The misreading
Popular writing reduces Scorpio to sex, which is one topic in a house that also covers debt, inheritance, grief and shared control. The common factor is not eroticism; it is that all of them involve something you cannot manage alone.
The genuine difficulty is control. Scorpio placements manage situations rather than trusting them, and Taurus opposite offers the correction: taking something at face value and not investigating it.
What actually shows from outside
Scorpio placements are widely expected to be obvious, and they usually are not. The sign conceals by default, so what people notice is an absence: questions that get deflected, opinions that never quite surface, a sense that more is being held than said.
What does show is the intensity of attention. Scorpio placements pay attention completely or not at all, and being on the receiving end of the first kind is memorable. That, rather than any of the darker imagery, is what people are describing when they say a Scorpio placement is intense.
The exception is Scorpio rising, where the concealment becomes the manner itself and is therefore visible.
Questions people ask about this
Is Scorpio ruled by Mars or Pluto?
Traditionally Mars, in modern practice Pluto. Both are worth reading, since they describe different aspects of how the placement operates.
Why is Scorpio associated with sex?
Through the eighth house, which covers everything held jointly. Sex is one item on that list rather than the theme of it.
Are Scorpio placements secretive?
They withhold by default rather than conceal deliberately. The reasoning is that information given away cannot be recovered.