Possessed Space Marines

[Kol Saresk]

No, all he did was give them all the ability of that occulus anima or whatever that absorbed psyker abilities and then reflected them. Spear was just able to do it on a much larger scale without the thingymabob.

[Lord_Caerolion]

I remember him describing Spear/culexus-person as psykers at various times in the book, not just have them use the Animus Speculum.

[Kol Saresk]

I remember the daemonskin and its ability to let him absorb memories of those he ate and that he was a Black Pariah which was supposed to be even rarer than a regular pariah and that if he ingested the DNA of a psyker, he could reflect their entire power back onto them and make them go POOF! And that the personalities survived in the daemonskin until he purged them, although one survived because he lost focus during the purge. I don't remember a whole lot else but it seemed more like the daemonskin did most of the work.

[Corsair]

Interesting topic, just thought I'd throw in my two spacebucks:

 

The loyalist Exorcists are routinely possessed and then exorcised as a part of their becoming full Space Marines, and I think it is unlikely that they sprout extra arms, etc routinely during the process for successful candidates (although it could well happen in isolated instances I guess, perhaps rectified by surgery and/or death).

 

Based upon this, I think it can most likely be safely assumed that, in addition to things like willpower versus strength of the daemon, pacts with daemonic entities versus forced possession, etc, that ritual bindings and various sorceries could probably be used to determine both outward appearance and the power and nature of the symbiosis between host and daemon.

 

Indeed it wouldn't surprise me if that would be a primary way that renegades do enter into these pacts where these are made voluntarily, as I doubt the more rational, less devoted warriors are thrilled by the idea of freely giving themselves to something that wants to eat their souls without some kind of protective buffer.

[Lord_Caerolion]

Well, it's interesting to note that the latest Exorcists fluff makes no mention whatsoever of the possession of their neophytes, instead having them focus on rituals and "sorcery". Well, sorcery in the sense that they use markings and iconography to have effects against the Warp.