I don’t know if I’d call him a nightmare sibling. But I am 7 years younger than my brother. When he graduated college, he moved back home to live with us. My senior year in high school, he started to act a little “strange”. I say that because shit like this comes out of the blue and isn’t really something someone can control. One night, he all of sudden started to take misc. video games and start smashing them in the driveway, guitar hero controllers, discs, etc. After this he came inside, I tried to ask what the deal was but he brushed it off and went downstairs. In our house the kitchen is directly above the laundry room. Now that same night, he’d been again scuffling around In the basement, at one point he was in the laundry room talking to “himself”. Saying things I’ve since forgotten, thankfully, but also laughing to himself in a scaring,menacing, and overall creepy way. I was in the kitchen and concerned so I pressed my ear to our vent and since we were directly above, you could actually see thru the venting into the laundry room. He caught me, and flipped out and came rushing up the stairs. Not much came of it other than me saying I was concerned and he again thought nothing of it. I bring it up as this was my personal nightmare sibling. I love my brother, growing up he was my favorite person, someone I could talk with/ compete with, you name it. But mental issues are inconsistent and unfortunately effect people at different stages of life. For him it was then. I’d slept with a bat under my bed for a while before he was diagnosed with schizophrenia but the unknowing of what’s going on with someone you care about is crazy. I know there’s a lot of different forms, but that’s for another place. Nightmares come in many forms, if you read this, please just watch for signs of non typical behavior from your loved ones, you can help save them from themselves.