Based on my understanding of a small set of ancient authors and their translaters, 8th house signifies idleness, the process of dying due to that idleness, the death itself, and inheritances from one's partners, sometimes one's parents.
There are many other factors to consider, however. Of the three main factors (planets, signs and houses), I find the planets and signs to be more important. So the first question I would ask is, where is the Sun? Then, it depends on which six planets are in there. If we take into account the three modern planets (Uranus/Neptune/Pluto), there are 210 planetary combinations possible. After that, what sign(s) are they in, and are they all in the same sign? Then we have to consider the house rulerships of those planets.
Houses and signs are important, but the planets are most important, in my opinion. So the planetary combinations completely change matters, even when we have two or more charts where six planets are in the same 8th house.
Now the combinations themselves, there are positive combinations. Venus/Mercury makes people talented in the arts and music fields. Mercury/Moon makes very perceptive and somewhat intelligent people. Mercury/Mars people are good at arguments and competitive. Mercury/Saturn makes those good at studying, thinking deeply, and makes the person fascinated in occult and philosophical enquiries. Moon/Jupiter can make the person popular or have a substantial inheritance. All this despite being placed in the 8th, because planets are stronger than houses.
On the other hand, some combinations are particularly harmful (note I only use the seven planets). For instance, Venus/Mars and Venus/Saturn both signify sexual problems. Venus/Mars can mean being overly-promiscuous (putting the native at risk of catching venereal diseases), or adultery, or it can mean being a rape victim, or having a partner who was a victim of violence or sexual crimes, etc. Venus/Saturn can make the native seek unnatural sex, from the relatively innocuous to the really dangerous (bestiality, sex with dangerous objects, sex with people who have AIDS, etc). Venus/Saturn can also lead to marriage/partnership with an older person (which isn't necessarily bad) or someone who is infertile or someone who already had children (again, not necessarily bad).
However, to know the specific pros and cons, we need to consider the sect and the zodiac signs, as well the bounds/terms the planets are in.