I know this will sound crazy but i have had this 'spirit' i guess in my head for months now.At first i thought it was just my imagination or random thoughts.But eventually he started taking on his own personality and commenting on things i did.I thought i was just experiencing delusion from stress but then weird things started happening.Our Tv started changing channels when no one was near it or touching the remote.Window shades went up by themselves and our doorbell rang at random times.(we checked, the doorbell is not broken and no one was ringing it). Then he started telling me things before they happened and I started having dreams that predicted things.Even weirder is that I started draining batteries.I went through five packs of brand new duracel batteries one day.Even now he ( i refer to him as he because he refuses to give me a name.He says its for 'my own good') is helping me write this.I have no idea whats going on.Since he came into my head.I've seen shadow people,  and these weird small beings, i'm not exactly sure what they are and other things.

Can somebody please give me advice?

I don't want him to leave, i just want to understand.
He has told me he is not an angel but not a demon either.Every time I ask him his name he says I already know it.

Can anyone help me?

Riddle me this. If a demon was a demon, would he let you know or would he deceive? Deception does not have to be given in lies. It can be given in half truths. Even if he was not a demon, why would a spirit want to live it's life through you, unless he did not want to leave this life? His life is his life and your life is your life unless you invite him into it.

Command him in the name of the One true God of love and light that he leave you be unless he is sent by God. Your choice.

take it easy.

Ok, look, demons will deceive but not all are bad as not all are good. If he is living through you that means he's picked you as a familiar. Demons aren't that of satan, nor that of god. They are the betrayers of both. I don't think he wants to hurt you, but I think you should insist on the name. Has anyone close to you died? Like a childhood friend? Point is, banishing him will do no good. Once you're a familiar it will be hard to deal without your leech. <--sorry if this offends---

Think of him as your guide. He'll probably do his best to protect you, but like all. . . for a fee. A daily dose of your essence is all he needs. Be careful though, he might/will perhaps get greedier and take more than is needed. In order to gain control in this relationship you have to learn his name(which is why most don't give out their names). Its like an access code.

Look at it this way you both provide from each other. To one another its like you both are drugs. If he went away it would feel like being addicted to heroine and suddenly been cut off. Same with him. . . if you cut yourself off to him, then he would have to search fast for another or suffer an agonizing death (which he had probably gone through multiple times before. If that is so you might have known him in a past life and your scent is similar, making him think you're one and the same. Hmm. . . need to think about that too. . .).

um. . . well. . .yeah. . . no more I can say for I really can't say anymore.

Um. . . be careful with sending them into the light kind of spells. Even though a person stuck to the earth is not a good thing, if you do it wrong (even by accident) it could make her angrier. My familiar had a problem like this, but his little brother seem to get along with this spirit. Granted my familiar treats his little brother like crap ("because that's what my siblings did to me, now its his turn!") so naturally the person and the brother had hatred and unresolved issues in common.
Soon the man was tormenting my familiar and I couldn't let that happen. My familiar tends to be susceptible to spirits following him. This one wasn't good. . . not only anger, but a rapist. The little brother told us. We also found out that the little brother was making deals with said man. It was upsetting, but the light spell went terribly wrong because my familiar was not giving his all to save his brother. IT got mad. . . very mad. . .
As days went by he gradually got bored with the brother and didn't bother us. Now something more terrible is terrorizing my familiar and his sister.

Talking won't really help, for they are not that rational about being dead, or just really don't care about the living. This woman, I think, isn't trying to harm you. . . keyword is "trying". I think her mouth is open for a reason. Like eating you have to open your mouth. In order for them to become stronger they need live essence. Some just act normal and sit close to you. . . some are so weak they need their mouth open.
All the same, just put up a barrier or a protection charm to ensure your essence is in one place.

There are way too many do-it-yourself types willing to lead the unsuspecting down a path of the good, the bad, the ugly without any real knowledge that all are not of the light.  As a medium you want to only address those of the light.