JMO... My brother was always scared when he was little. More often than not, he would end up in my room, sleeping with me. Also, when we spent the night at our grandparents, we shared a bed until I was probably 15. We also still share a bed on vacations- I'm sure her brothers weren't thrilled about sharing their room/bed with their little sister, but I bet they were happy (? not sure if that's the word I want) that she came to them for comfort since she was their baby sister. I was excited that my brother thought I could protect him.
Just my 2 cents, and a scenario that isn't sinister.