Re: Theo/Sirius.
That is a complicated question with no quick and easy answer. I have heard many theories. Some involving organizations that uphold the integrity of the timeline and dispatch irregularities. I have heard some speak of the bus like it is an entity of it's own, raveling through the fabric of space and time. All ideas I have heard have merit. I see the bus more so as an acting agent of time itself, seeking to safe guard the keystone moments between worlds. To keep time in tact. I suppose everyone seeks the answers they want with the basis of the knowledge they have.