Maybe your brother lucid dreams this? or you may be in a dream state yourself and using a extra sense of speech which your brother can interpret. In any case, don't worry, maybe talk about it to your brother and make it exciting rather than scary.
My brother isn't lucid dreaming because I one gained full consciousness while I was doing the sleep talking and I was like "what am I doing." And I went back to sleep
My brother isn't lucid dreaming because I one gained full consciousness while I was doing the sleep talking and I was like "what am I doing." And I went back to sleep