Imaginary friend
When my daughter was 4 she started talking about an imaginary friend. At first it was cute but a little creepy. She first mentioned them while at a sleepover with family saying "they were watching" her aunt blew it off but reported it and mentioned the name only came up a couple of times but that time made the hair stand on the back of her neck. We laughed it off as a little kids imagination.
For months my daughter brought the friend up. Talked about the games they'd play and how funny her friend was and I thought it was harmless until my daughter came out of her room crying and said her friend scared her. We aren't talking about crocodile tears, this kid was hyperventilating and wanting to sleep in my bed terrified.
Took me a minute to get it out of her. Her "imaginary" friend had told her their whole family died in a fire, that the imaginary friend did too as well as their grandma and their dog and that my daughter and our family would die that way too. Again my daughter was FOUR. That was when I told her she wasn't allowed to play with that friend anymore and that she had to ignore them.
Found out 8 years later that the same imaginary friend had been with her when she swallowed and choked on a nickel. She had to have it surgically removed and I think the friend may have been behind it. That was when she finally gave me a description of the "friend" she had been seeing. A little girl with long brown hair and a stripped long sleeve shirt with solid black eyes and was giggling and jumping in the bed when my daughter swallowed the coin.
We haven't said that imaginary friend's name since my daughter was 4 and won't. I didn't put it in here because I have no interest in inviting that thing back in our life but I will say do not blow it off if your kid mentions an imaginary friend. They see things we can't and that friend could be dangerous. Pretty sure it almost cost my daughter her life.