People overlook the clearest advantage to sharing a room: there's a 50/50 chance the monster under the bed will eat your brother instead of you.

My sister and I usually had bunk beds (until the point when I was ten and she was eight and we moved into a house where we could have our own rooms), but we had to sleep in the same bed when we visited my grandmother's house. I wanted to sleep in the middle of the bed, because otherwise I woke up with her crammed on top of me, so I told her there was a monster that only ate people who slept in the middle of the bed and bravely volunteered to face it. She still hasn't forgiven me for the apparent years of terror I inflicted on her. /irrelevant thoughts on sharing