The realm of Geozan Reality known as the Dreamlands is both an extension and reflection of the Spirit Realms.  It is distinct in nature, however, with its own laws and characteristics that are quite different from those of the Spirit Realms.
	The Dreamlands are essentially the communal creation of all sentient creatures who dream.  Most sentient creatures possess both material and spiritual elements. Usually, the material elements are more prominent.  Humans, for example, live their lives almost entirely in the material world.  (Other species can express a different balance of matter and spirit.   The Fae, for example, seem to be much more attuned to the spiritual side of their existence, to the point where at times they seem to be more spirit than matter).  Through dreaming, a sentient being extends their consciousness into the spiritual realms, and for a brief time, expands upon the limited spiritual elements in its material life.  The dreamer becomes, for that ephemeral instant, more aware of spirit than matter (at least in their consciousness).
	While dreaming, the dreamer "creates" a spiritual environment into which the consciousness is placed.   These dreamlands are entirely dependent on the dreamer for existence.  When the dreamer awakes, the dreamland no longer exists.  This is similar to the old riddle, "if a tree falls in the forest, and no-one is around to hear it, does it make a sound?"  The Dreamlands answer is, the tree doesn't even exist without a dreamer, let alone make any sounds.  For you physics students out there, the situation is similar to Schroedinger's Cat - you can't determine the existence of the Dreamlands until you create it.
	Well, at least most of the time.  Things work as stated above in the vast majority of cases.  But there are exceptions.   One fairly simple exception occurs in the instances where dreams are shared between two or more individuals.  This is fairly rare among humans, but occurs slightly more often in some other species (such as Hssuga or Kri'ik).  When such an instance occurs, the shared dream is dependent on both or either of the dreamers involved.  Elements which are common to both dreamers will exist independently of either dreamer.  Elements which are specific to that dream depend upon the shared dreams of both to exist.  If either dreamer is not involved (i.e. their dreams have drifted away from the other dreamer, or they awaken or otherwise cease to dream), then that dream-element ceases to exist.  Such situations are easily understood, for the most part.
	There are, however, situations which are not fully understood, even by experienced Spiritists.  Some beings are capable of actually leaving their own dreams and entering the dreams of others.  This is not uncommon among latent Psychics (through the Pneumosis Discipline) or among those with high Sensitivity to the Spirit Realms.  It is not always voluntary (and initially, is seldom conscious), but with psychic training or magical training, the dreamer can learn to control this ability.  Such an entry into the dreams of others is a far different thing than it might seem.
	As an example, consider a young woman who is intensely attracted to a young man in her village.  She will, from time to time, dream about him.  He will seem real to her in her dreams (at least, as "real" as anything in a dream appears), and she may have dream conversations with him, etc.  He is not, however, actually that young man in a dream.  He is a spiritual construct of her consciousness.  Thus, he acts as her consciousness imagines him to act, and not as he actually would in "reality."
	But suppose that this young man were actually a latent psychic with talent in Pneumosis?  Suppose that while dreaming, his latent ability manifested itself, and he drifted into the dreams of others.  Upon entering her dream, one of two things would happen:  1)  he would immediately adopt the role of her dream-man, but would then act independently of her consciousness, or 2) he would manifest within her dreams as something other than himself.
	Manifestations in such an intrusion could vary greatly, depending on how the young woman's consciousness reacts to the intrusion.   If she were secretly in love with him, then she might fully accept him into her dreams, surrendering a large degree of control to his consciousness.  If, on the other hand, she was suppressing her attraction to him in the material world, her consciousness might refuse to accept him as himself, and instead perceive him as a threat - with a suitable manifestation (perhaps as a wolf, for example).  Such instances have in some areas led to folk tales of witchcraft and demon possession, with subsequent prejudice against the psychic.
	Can such a dream intruder exert control over the dreamer?  Sometimes, but only in a limited way.  The intruder's actions will largely depend on whether they are conscious of what they are doing.  If not, their actions will be typical of the kinds of things that one does in a dream - reacting according to the priorities of the subconscious mind.  If the intruder is aware of what he is doing, he can attempt to "steer" the dream through control of the imagery and sensations in the dream.  This is a complex and dangerous task, but an experienced dreamer who understands the symbolism of dreams (to the other dreamer) can often "give" someone exactly the dreams he intends them to have.
	In the example above, the young man might decide to force his own appearance into the dream, rather than manifesting as the wolf that the woman's consciousness wants him to be.  In such a situation, the woman might react in several different ways - she could flee, rather than face him as he is, and thus have to face her own feelings.  Or she could face him, and in the process her own feelings about him.  In this case, since he is actually the young man's consciousness, her feelings must manifest as something else (perhaps as manacles which bind her feet and hinder her attempts to flee him).  Dreams are built upon symbolism, and the Mythguide should feel free to be as surrealistic and creative as she wishes when describing such encounters.
	Finally, there are elements of dreams which are not truly dependent on any one individual.  Rather, these dream elements depend upon racial or species-shared symbols which are so universal that they attain a spiritual existence of their own in the Dreamlands.  These are powerful dream elements, and experienced dreamers are cautious when such are encountered.   Sometimes, entities of the Spirit Realm can enter the Dreamlands and attain such a status, mutating into a dream entity.  Other dream entities are sometimes created when dreamers die while actively dreaming (meaning that they are outside their own dreams, and projected into the Dreamlands outside of their own consciousness).
	Dreamers of one species seldom interact with the dreams of another species.  This is probably due to the differences in psychological makeup between the species.  Sometimes such encounters do occur, though - usually in response to a universal dream element which is shared by both species.   Such meetings can be both momentous and confusing, as the dream imagery and sensations are often very different for each dreamer.
	Some Random Ideas for special Dreamlands entities:
	"Virus Dream" which originated as a shared dream, and which "infects" other dreams to continue its existence.
	Schizophrenic - repressed, latent psychic Schizo side (one of his manifestations) develops its existence in the Dreamlands. Might be able to split off into its own independent existence in the Dreamlands.