Hi, I have been involved with a friend who says he can Lucid Dream and enter the dreams of others but is also a pathological liar… I’m not saying I don’t believe in lucid dreaming myself for I believe in a lot of paranormal occurrences and actually am an active learner pushing myself to be able to Lucid dream on command. I have gotten close just it was the mindset that I had been in so long that was making it hard to do it. But anyway, So this kid keeps appearing in my dreams whenever I push him away as a friend. (I don’t really want him to be my friend because I feel as though he really wants to hurt me, to be frank he almost got me to kill myself when I was younger because he was depressing the shit outta me) So what I want to know is does anyone know if it is possible to actually hurt someone in a dream as well as what should I do about it if it is posssible? He is a pathological liar so every time I bring it up to him that I know he was in my dream he just says I’m crazy. Help on this topic would be appreciated! 
I don’t really believe in shared dreams/hacking into other’s dreams as it’s not scientifically possible and there’s no actual proof of it. If someone is threatening you to hack themselves into your dreams, I would suggest not to believe them. If you see him in your dreams, you should know, that it’s certainly a character controlled by your subconscious and not by him.
About being harmed in dreams… It’s totally not possible to be physically harmed in any way. You may die, get hurt, become sick in a dream, but you will still wake up fresh and alive in real life. You should look at dreams as hallucinations created by your subconscious, which you can control if you become lucid during them. There is no danger involved while dreaming and you should dream safely and without any fear.
On the other hand, if your ‘friend’ keeps appearing in your dreams, you should definetely get a habbit of doing RC’s whenever you see him or think about him. This may prove useful in achieving a lot of DILD’s.
I dont personally believe in shared dreaming since as previously posted, there is no scientific proof that its achieveable (as awesome as it sounds) but then ive never had any sort of experience with it. So going from this stand point- Your friend who keeps appeaing within your dream…may be just your subconcious manifesting him, possiblely because your concerned about the chance of him ‘hacking into your dreams’ or him appearing somewhere or having him generally in your thoughts and because its still in your mind, your subconcious is using it. You cannot be harmed within your dreams to an extent that they affect you in real life, yes it can scare you…you can have the usual nightmares, but its still what your mind has conjured, nothing else.
My advice, either try not to worry about him so much…or otherwise, take action within your dream itself…If he reappears, ask him to leave or even build a sort of defense within your dreamworld; banishing magic, traps, guards dogs maybe even some sort of ‘black hole’ that sucks him to another place…lots of different things you could try.
Also if this ‘friend’ of yours is troubling you so much, causing you so much anguish…no offence intended, but is it really worth continuing this relationship? Talk to him about it
I think it’s possible to have a shared dream. When I was little, my mom said she got up in the middle of the night to use the bathroom and heard me and my Dad talking in our sleep; holding on a conversation, in two seperate rooms. I was never really close to my Dad, but he is my biological father. My Mom would not have lied to me, so I believe her even though neither of us remember dreaming at all that night.
That being said, I don’t think this guy is invading your dreams. I think it is more likely that some part of you feels guilty for pushing this guy away. Dreams come from your own head, not someone else’s.
I suggest talking to him about how he’s making you feel. Let him know you would like to stay friends, but he needs to stop bringing you down. If you are lucid when he shows up in your dream, give him a hug, put a leash on him so you feel in control, or just turn him into a slug and step on him, it’s your dream.
If your religous, You could try praying that you don’t dream about him, you could also try telling yourself before bed, that you will not dream about him tonight.
But most likely, it’s your own internal conflict causing these dreams, not him, and to get rid of him, you have to deal with your own thoughts and emotions.