It seems an odd situation. Does your daughter not have someone her own age to talk to? If she doesn't that can make a bus ride boring and no wonder she plays up if others do.
Does your daughter have to change schools soon now that she is older? In Australia, 13 is the age when we start high school. We don't have elementary and middle school and all that.
She likes to talk about the imaginary stuff she makes up, so she might perseversate on saying "Amnesia-causing basement," or asking the other people on the bus to "basement her" or she might talk about different aspects of the "Lollypop," which is the name she has given her "Superhero School" in our back yard. The top of her play fort is the "Principal's Office" and her swimming pool is the "Superspeed/Flying/Breathing Underwater/Mermaid/High School Room" for example.
She wants friends, but sometimes her extreme behavior scares them and also they often don't know how to respond to the things she says. Personally, I love her amazing imagination, but I know what's she's talking about while other people often do not.
She may change schools to attend a high school in our school district next year.
For us, the transition to high school usually happens at age fourteen or the ninth grade and high school ends with the twelth grade (age seventeen). Our elementary schools sometimes go from preschool (age three or four) or kindergarten (age five) through either fourth or fifth grades, then middle school starts either in fifth or sixth grades and goes through eighth grade.
