Others Entering Your Dreams
A while ago, I had this dream once where I saw someone I knew & am not on good terms with & it was like they could see me. Someone in the dream told me that when someone has strong negative feelings towards you, they can enter your dreams. Not "a memory of them", but actually them as they currently are.
I had never heard this concept before at all, but I'm inclined to believe it, especially after experiencing that dream.
(If anyone's curious what my PFP is, I had a dream I saw mother nature once & she looked like this.)