Free's are bound by the limitaions of his or her .. or its .. species of free ... un-dead brought back by a Necromacer are bound to the Necro. Fay creatures are generally bound to the law of the land ... Dead spirits who have crossed back over follow the general rule of vampires ... sun is very unhealthy ... you can only cross a river it the passage is covered in Grave Dirt. You can freely cross back and forth between life and death if you are strong enough ... only a Necromancer of equal or greater power can banish you back the the river and seal you beyone the ninth gate. A necro of lesser power can banish you only with the propper equipment that raises their stats to yours or higher. If you defeat a Necro of lesser power in battle ... if the body is undammaged .. you can inhabit it, though you will not gain its power. Spirits that have crossed over can inhabit any dead mortal body untill it fully decays .. then they must inhabit another.