I did some work on possession spirits a while back, that could be expanded to Shedim easily enough. They usually show up as Free Spirits, which is a problem, because Free Spirit rules don't exist yet. Shedim might get a writeup in Street Magic, but they might not (of all the things introduced in the Threats and other sourcebook series, only Insects and The Wild Hunt ever got a place in the basic magic book of previous editions). Free Spirits, on the other hand, have been in every version of the magic book, so rules for free spirits in general are looking pretty likely.

Once you have Free Spirit rules at all, Shedim are easy enough to convert (those nasty karma draining powers can be a pretty straight port).

Don't the Shedim normally possess dead bodies? Even the master shedim simply use regeneration powers to make dead bodies appear to be living bodies. Shedim are big on causing warfare and strife, not so much on getting people to volunteer for Shedimification. They could, I suppose, trick people into drinking poison Koolaid in order to possess the body right at the moment of death, but there's no reason to have any organization at all at that point - you'd be better off just grabbing people off the street and injecting them with Perfidus Epsilon Toxin. Shedim don't need to coccoon people for weeks, and they don't make bug parts grow out of their hosts. So Shedim have no need to explain why people vanish for weeks or years at a time with no face-to-face contact with family or friends.

So I couldn't see them making a UB type organization. They don't need it. The only reason they sponsor groups like the NIJ is because they want young people to kill each other.

---

That being said, there are a lot of unanswered questions about the Shedim which we may not get answers to for a long long time:

Who's conjuring up all the Shedim? Is it other Shedim? Corrupt human mages? Ghostwalker? Heck, did someone just leave the Shedim faucet on?

What do the different types of Shedim do? To an extent it doesn't much matter. Shedim are possession spirits, and a possession spirit just adds its force to the physical attributes of the host - so we don't need to know what their physical attribute mods are. But still, there are crazy jellyfish looking ones, and evil snake ones, and a whole bunch of others - which probably correspond to five spirit types that grant different powers to the spirits they possess (how much you want to bet none of them is a "spirit of man?") - and we have never been told enough about what the different types of Shedim do to hazard a guess as to what categories they belong to.

What do Shedim want? Other than getting their hands on corpses, what goals do they have? :shrug:

-Frank

I believe that they can possess both living and dead bodies, it is just that dead bodies don't have someone inhabiting them already, so no resistance. I seem to remember that the Shedim were making out to be a big deterant to mages spending long amounts of time away from their bodies because a Shedim could come along and snatch it up while you were out.

They did that in SR1, SR2, and SR3. I don't think it's much of a stretch to assume they'll do that in SR4 as well. Not a huge deal for Shedim, dead bodies have lower physical attributes than live ones (the Zombie rules had a simply halved physical attributes for dead hosts, but the Shedim used to have an immensely complex chart based on the age and condition of the corpse).

So what you're looking at is an Earth Shedim having a body of Force + (Some Reduced Corpse Body Value) instead of Force + 4. The Shedim might be able to pull ahead by grabbing the body of a big troll, but that doesn't sound that bad for a creature giving up its ability to materialize anywhere it wants.

-Frank

Why bother using shedim then? What makes them and wraiths such great opponents is that they can severely cripple a character. Besides, last time I checked zombies were too stupid and fragile to use suicide bombings as a devastatingly effective tactic. Treating shedim like zombies is just... It's so wasteful.