Let's Make Some Magic (part II)

A traditional element of fairy tales and legends is the presence of magical creatures.  When I refer to magical creatures, I am not generally referring to fantastic creatures.  Fantastic creatures like orcs and elves and dragons (in most settings) tend to follow the same basic rules of nature as humans.  Those folk I cover in a different series.  Magical creatures, then, are things from some other realm of reality, beyond our physics and everyday experience.
    Gods (as discussed at length in other posts) can certainly be viewed as magical creatures.  They have power beyond human understanding.  Sometimes they reside in another realm and must contact their believers through dreams/visions, omens or other signs.  Because these beings are of such great power (though your gods might not be, fine plot point that) authors often limit their interaction with the world.  The power of the gods is some worlds is based on their number of worshipers.  In many settings, the power of the gods are loaned in small measure to their followers (allowing certain magical abilities), but this is limited by the physical capacity of mortals to contain/manipulate/contact this power.  Often, the relationships and subsequent agreements among the gods are what limit this interaction with the material realm. 
    Angels, devils, demons and such are generally lumped with the gods, but often play a different role in a fantasy setting.  These are often the go-betweens for their masters, delivering instruction, appreciation or chastisement, as appropriate.  Immortality is not uncommon in these beings (created by the gods at need?), but usually they can be killed with concerted effort.  When they do reach the material world, they tend to disrupt nature and reorder things to their liking.  Demons seem to be a greater part of Eastern tales and their defeat often has a spiritual element.  However, at other times these creatures are too powerful and can only be overcome through trickery or deceit.  Their defeat sometimes means death, but often results simply in banishment from the material realm (either for a set period or until they figure out another way to get here).
    Ghosts and spirits are ethereal manifestations of the soul.  This variety of magical creature could be from a human spirit leaving its body or it may be from a river wanting to communicate with passers by.  These creatures are often incorporeal and take on all kinds of guises (trees and such looking more human, ghosts may look like the deceased at any stage in life or like something else entirely).  These creatures are usually tethered to a specific place, whether it be the place of their death or within a certain range of their physical form and have limited interests (who killed me?  who chopped down my forest?).  Their power, similarly, doesn't usually extend outside of this range.  In stories, these creatures are often simple plot devices to charge the protagonist with a quest.  Alternately, these beings may serve as an information source for characters (perhaps consulting an ancestor).  Spirits of the deceased do not usually mess with the physical world unless there is something specific keeping them there (though Heinlein's Martian "Old Ones" are a notable exception).  Spirits of nature don't usually bother anyone unless something messes with them.
    "The Fey" is one of the names for creatures that exist within two worlds (see the film "Pan's Labyrinth" for an example and just because it's a great movie).  These creatures might be worshiped as gods in certain settings.  Often, people residing in the "real world" do not understand the rules that govern these creatures, but it's important for the author to know them.  How do they pass between?  Why do they go back and forth?  Are they different (look/power/etc) in the different worlds?  These "rules" often provide the motivation for these creatures.  Additional examples can be found in Susanna Clarke's Jonathan Strange & Mr Norrell or Patrick Rothfuss' Kingkiller Chronicles.
    Magical creatures are a mainstay in Fantasy settings.  They have been used in a variety of roles, from character to plot device to story focus.  In To Reign in Hell, they are the only characters.  Because they operate outside of our physical limitations, they need to have some of their own to limit their influence on our world.  These limits can be as simple as a pact with the other gods or as complex as the movement of the stars.  Their presence can add whimsy, menace and wonder to any world.