as i said in the last post you made, you need to protect and purify your home. energy can build up and pool sometimes it can take on forms. without more detail into this being i cannot say for certain what it was. an Incubus/Succubus is a sexual demon who feeds off energy during the act. to have one sneaking around your house is odd, though there are cases where they'd wait till their victim was asleep. try some protective charms around your bed to be safe.
i think it's just built up energy, for a dream character to appear outside of ones dreams is strange, but you could will a being into existence with your own energy. it could be someone, but i doubt it, most people who project don't sneak around people's houses. if they did, you'd probably recognize them, they wouldn't appear as a dark figure.
i you should read up on Succubus and Incubus if you wish to fully know about then and their effects. basically though they're sexual demons, while not all evil, they are dangerous, since demons commonly do whatever they feel will get them what they want. if you're being attacked by a Succubus/Incubus, you'd feel tired and drained of energy, you might look or feel sick, pale, weak. just cleanse and protect your house. it should get rid of all negative energy, weaker beings, and make it harder for stronger creatures like Succubus to enter. the easiest way i know to keep a demon away is to mentally put up a block, if you only want positive beings in your home, state it, you could put a plaque on the wall stating it, or say a chant stating you only want beings who do not wish to harm, or just think it when you enter your home. a protection spell on your home should do the trick though, be sure to recast. annually's fine, but some people do it more.