I've been wanting to make a forum post about this for a long time, but never could really figure out how to start it or explain what I've been experiencing. (And I just know everybody is going to think that I'm crazy.) Now chances are this is going to be very long, so I'm going to highlight each important question. I suppose it's best to start at the beginning of the story.

It all started three years ago when I began lucid dre... NO! wait we have to go back farther than that!

When I was in kindergarten, I had a dream where the sun was blocked out by a giant mechanical bird. I thought that all the plants would die, then there would be no more oxygen and everyone on earth would die.
But a dream character convinced me that the bird would leave, and once I was convinced the bird left and the sun shone again. I only looked at her for a moment, and thought nothing of her for the next decade.

I once had a very spiritual seeming dream again when I was about 10. (This dream isn't in my DJ but it will be someday.) In the dream there was a party going on celebrating somebody's life, taking place at this beautiful tropical beach resort. I saw her there too. But my memory of seeing her there is much more vivid.
Somebody was talking (be it to me or someone else, can't remember) about someone who was on their 10th or 11th life or reincarnation. But I'll get more into past lives later.

Until I started lucid dreaming, and met my dream guide (on the very first night that I started lucid dreaming at that.) I began to notice that I was seeing her alot. Most lucid dreamers never mention dream guides, and those that do seem to mention them pretty rarely. For me, seeing my dream guide was, and still is a very regular part of lucid dreaming.

This isn't something I want to change. Seeing my dream guide alot is great in fact, for I get extra help in learning dream control and somebody that I can talk to. But I found it weird that I was seeing this person even before I knew what lucid dreaming was. Anyone else experience this?

As I got more experienced, I came across an issue when writing about my experiences. I didn't know my dream guide's name, so I decided to ask her. The first couple times I got a jumbled response due to the dream being unstable or something interrupting my question.
Eventually, there was a time where I was able to ask the question without anything interrupting. She started listing names. I interrupted and told her I needed one for my dream journal. She told me to pick one.

This seemed weird, anyone else had their dream guide ask to be named by you?

Then started coming the things that I didn't really want to have happen in my dreams. I was happy to just learn lucid dreaming. The only reason I wanted to learn lucid dreaming was for artistic inspiration and more importantly to practice some degree of escapism, in having a private realm where I could escape the troubles of my waking life.
I began to notice the occurrence of a dream villain. I decided to name him Jonathan after a bully from my grade school. (He sort of looks like an older version of him.) He would attack me and my dream guide and force me to wake up. He seemed to be able to execute dream control, but seemed much more powerful and experienced than me.

This is where I start getting some more serious questions. Does anyone else have experiences with a persistent dream villain? Why is he able to execute dream control even more powerful than me? Why is he evil? Why does he even exist?

I asked Lia about him, and I began getting some strange responses. One time she told me that he was able to move between dreams, and that he actually didn't exist in my dreams to begin with, and a moment later I had this truly horrifying idea that this wasn't just a normal dream character, but rather was some sort of demon that attacks people through their dreams.

Is this just my subconscious creating a story and attaching it to my lucid dreams, or is this a legitimate spiritual issue? Either way, I want to know how to stop this.

I have encountered a number of other dream characters as I've gotten more advanced. Named all of them and begun to track their traits. Aside form Lia, my own dream guide; And Jonathan, my dream "nemesis". Perhaps the most prevalent one is a man I named Marcus.
The strange part about all of these characters is that they have very distinct personalities, and they all act as though they are aware that they are just dream characters. They know that I am the dreamer and that it is important to respect me, and I give them the same respect back, even thought these people don't even actually exist, but they seem so real.
Having these characters around can be nice at times, but sometimes I feel like it is something of a bother to me. When I first began lucid dreaming, I wanted to be alone in my private world. (Agian, escapism.) But now, I'm keeping track of a growing list of dream friends. I just thought that was a bit ironic.

Up until this point most of this has just kind-of happened, but, there is just one dream that is such a big bother. It puts fourth the most convincing argument that I am infact having foreign "dream invasion" I will link you to the full dream journal entry here but I will sum up what happened and why it bothered me right here:

I was lucid dreaming that I was in some sort of town, and had decided to destroy the town to practice my own dream control powers. I had only gotten past one building and killing a couple of dream characters before I was approached by a witch woman in a purple dress.
She told me to stop destroying the city. I replied by telling her that this was my lucid dream, and that I was able to do anything I want without repercussions.

This is where she gave the strangest response, and I quote: "You think that you can do anything without consequence?! That is not the case in your dreams!"

This is where I got weirded out. For one THAT IS NOT SOMETHING A DREAM CHARACTER SHOULD SAY! I was even more weireded out by the fact that she actually acknowledged that you can do what ever you want in your dreams, but then went back by saying that I am somehow special and that in my dreams there are consequences. What bothered me the most was that in my sort of dreamy sense, I could tell that she was telling the truth.

But it gets worse. I decide to summon Lia, my dream guide to deal with this dream character. Not sure what to believe, I want to remain in control of the dream, and show that I am superior to this dream character. She appears and I explain the predicament. She says nothing, but rather uses her dream control to conjure a large log and have it fall onto the witch woman.
Okay, problem solved.
N-NOPE! The witch woman bursts out from underneath the log and has become a big black and red spiky demon-nightmare monster. I think that I'm in for a fight, so I prepare to use dream control spells to blast the monster.
Then I remember that when you confront a nightmare, your not supposed to destroy them, but rather ask what they represent. So I do just that. The nightmare shrinks down and becomes a kitten. There is a note inside of the kitten's mouth that I know explains what that thing is. Lia is trying to get the note out of the kitten's mouth when I wake up.

Now I get even more bothered by this dream. For one, the tree trunk conjuring. Why would my dream guide do that if it only makes the situation worse rather than solving it? Heck if it wasn't for me asking the nightmare for purpose, we'd have both been nightmare demonmoster chow.
And why was she trying to get the note out? She is my dream guide after all, she should know everything about my dreams. Why didn't she know? My bloody dream guide of all people didn't know. I hate to assume, but I think the reason she crushed the witch woman was because she wasn't anticipating the transformation. And the reason she was trying to get that note was because she didn't know what that thing was either! This led me to believe that that thing was in fact foreign, or had come from outside my dreams!

I could go on with some of the less convincing and specific examples of this story taking place, but I don't think that would be wise. If someone were go through my dream journal, they would probably pick out more things that weren't right.

This leads me to my final question. Wether or not this is in fact a spiritual experience, and I really am being harassed by "dream demons". Or this is just my subconscious turning all of my dreams into an elaborate story, I want it to stop. I just want to lucid dream normally without this battle between dreams and nightmares taking place anymore.

I'm sorry I didn't get to touch on any more of the rather strange things I've been told or seen in my dreams. But I feel like I've gone off on a tangent. Perhaps getting my question about the "demons" answered will open the doors and allow for more questions to be answered.