Loss of memory of a random insane moment.

Okay, the oddest thing just happened to me. I was sitting upstairs in my kitchen working on my laptop, when suddenly my brother randomly stomped halfway up the stairs, said "What are you doing?" and walked back down. There was a wall between me and said stairs, so I couldn't see him and he couldn't see me. Of the 4 people that where in the house, one was sleeping, two where in the kitchen, and he was on the stairs, so there was no one that was in his line of sight. When he came back up later he didn't recall it, and thought I was crazy. There where two witnesses, me included, who say it happened, so I know I didn't just imagine it.

Also sometimes when he is alone we hear him whispering random things to himself, which he claims never happens.

What is going on?

I personally think he may be falling into a day dream and randomly sleep walking. Any thoughts?

I know sleepwalking sleeptalkers and it's not uncommon for them to wander around, say a few words to people, mutter to themselves, and not remember a thing when they wake up.

Sleepwalking.

My cousin used to run around with his eyes open while asleep, and speak to us even.

Schizophrenia.

Get him help

OR, he may be smart, and acting this way to scare you

Tell him to stop trying to scare you. If he insists he's not bullshitting, get him help.

Unless this was after he was asleep or something? Then it could easily be sleepwalking.

Schizophrenics usually can;t hold proper conversations, they'll keep switching from one thing to another, so if it's not sleepwalking,
you could also try to see how he performs in a long-ish conversation.

The obvious question is, around what time did this happen, and is it possible he was asleep at the time? Sleeping late or taking a nap? That does sound like sleepwalking behavior to me, but I don't know the context in which it happened.

Definitely sleep walking. Is he taking any sleep meds like ambien? My mom used to always talk in her sleep, so annoying. Once she started taking ambien though she would do all kinds of weird stuff. She would stumble into the tv room and tell us that our uncle's flight was canceled. The next day my mom is the only one who didn't know why my uncle wasn't there. We said, "you told us his flight was canceled last night!" lol. She didn't remember anything about it. But even without drugs, it's common for people to sleep walk, talk, etc. Maybe he could see a sleep specialist. I don't know if there is any medication for that. I assume it would be something like diazepam, but I dunno. It's harmless...unless he walks into a dangerous situation. You never know what might happen. Maybe get locks on his doors and windows for his safety.

This is a lot less likely than the other possibilities already mentioned, but here's another possibility....

You and your brother took two different historic paths up to the present moment. In your world, he went up the stairs, in his, he did not. Now you have a contradiction because your memory doesn't match his. This kind of event is extremely rare, fortunately, or a lot of things that we depend on wouldn't work reliably. But its not actually prohibited from happening by anything in current physics theory. Its just assumed not to happen because it generally doesn't, and because people would find the implications disturbing. I believe that such events exist because my 'muse' produced several verifiable ones as demonstrations. (I could have sought stronger and more numerous demonstrations, but didn't want to go down that path because I consider it dangerous. And since I did already went through a much more rigorous questioning and proving process for dream premonitions, which are also supposed to be impossible, I just took the universe y-piping at face value rather than questioning it further.)

No need to take my word for it though. If you don't believe in it, that's fine. Like I said, the other possibilities others mentioned are probably more common anyway.

^^^^ Reason why you don't post this in beyond dreaming ^^^^